Left 4 Dead Wiki
Mutation icon.png
"Each week one new Mutation is featured and the previous Mutation retired."

Mutation is the name for a set of modified gameplay modes, the first of which was released alongside the campaign, The Passing in Left 4 Dead 2. The Mutations are special game modes that were initially available for one week each before being retired, and replaced by a new Mutation each week following an announcement on the in-game Blog Post every Friday.

Periodically, a poll was conducted for players to vote for their favorite Mutation, which returned the following week as an Encore Mutation, meaning it would re-appear the next week (See below for Encore Mutations). With the download of The Passing DLC it is possible to choose what Mutation you get to play. All mutations were made freely available for play at any time on 07/24/2012.

Moreover, additional free custom Mutations created by players are available in the Steam Workshop.

Revealed Mutations[]

There are almost 30 different Mutations playable on all Left 4 Dead 2 Campaigns.

The following have been revealed on Valve's L4D blog in the scheduled order along with their taglines:

Mutation Tagline Date(s) active Mode(s)
Realism Versus You can't see each other but they can see you. Launch: 04/22—04/30/2010
DLC: 07/24/2012—so far
Effects of Realism are added into Versus, favors Infected side due to lack of outline glows when playing as Survivors, along with stronger Common Infected. A Blog Post by Valve left it to the community to decide if Realism Versus should be a permanent feature via an online poll. On week 2, the results showed that 68 % of those who took part in the poll wanted Realism Versus as a permanent game mode, which was implemented on the 21st May 2010 during the Mutation update.
Bleed Out Your health is a ticking away. Launch: 04/30—05/07/2010
Encore: 02/25—03/11/2011
DLC: 07/24/2012—so far
You don't have access to any First aid kits at any time. You start with pain pills and temporary health which cannot be permanently healed. The stages will only have pills, Adrenaline and occasional defibrillators. Random panic events appear to be one step away from being permanently on, and the Special Infected spawn rate seems to be doubled.
Follow the Liter Scavenge one can at a time. Launch: 05/07—05/14/2010
Developer's Choice: 09/10—09/17/2010
Encore: 03/11—03/25/2011
DLC: 07/24/2012—so far
The Director will spawn only one group of gas cans at a time, and until that group has been deposited into the generator, the Director will not spawn any more. If the group that spawns has more than one gas can in it the Survivors CAN pick both up so the Survivors are not necessarily limited to only picking up one gas can; they are only limited in choosing which group to go for. This mode requires everyone to stay together rather than running off to different places.
Last Gnome on Earth Protect the gnome at all costs. Launch: 05/14—05/21/2010
Encore: 05/21—05/28/2010
Encore: 03/25—04/08/2011
DLC: 07/24/2012—so far
The Survivors spawn with Gnome Chompski close by, which they must transport by carrying him all the way to the finale. The Infected will chase the Survivor carrying the gnome. The chapter will not end without the gnome being in the safe room or the rescue vehicle; thus, this mode requires the players to protect the Survivor who is holding the gnome.
Last Man on Earth You will become legend to the infected as the last human left. Launch: 05/28—06/04/2010
Developer's Choice: 08/20—08/27/2010
Encore: 04/08—04/22/2011
Encore: 04/13—05/04/2012
DLC: 07/24/2012—so far
Single Player
You will play by yourself without Survivor Bots to back you up. Only Special Infected will spawn. If you get incapacitated from a Special Infected which grabbed you, you will automatically revive yourself, but your vision will be black and white, which means if you do not heal, you will be killed if you go down again. To balance this out, the Director orders the Special Infected to run away briefly after incapacitation, allowing you time to recover. Defibrillators do not spawn in this mutation as there are no teammates to resurrect. There are also very few pipe bombs and no Boomers due to lacking Common Infected spawning in the campaign (though the Church Guy can still become a Boomer). Health kits spawn much more frequently than usual to help the player, especially on harder difficulties.
Chainsaw Massacre 4 chainsaws, millions of zombies. Launch: 06/04—06/11/2010
Encore: 06/25—07/02/2010
Encore (Xbox 360): 08/27—09/03/2010
DLC: 07/24/2012—so far
Survivors start off with a default Pistol with Chainsaws on the ground. The Chainsaws have unlimited fuel. Survivors can choose between the Chainsaw or Pistol, along with picking up another Pistol dropped by another Survivor for dual-wielding. For the duration of the game, no other primary or secondary weapons will spawn. Survivor Bots, for this Mutation, will immediately pick the Chainsaw as their weapon of choice. Common Infected are active earlier and may appear right at the start of campaigns when Survivors are not ready. They are also more active in attacking Survivors due to the noise of multiple Chainsaws.
Room for One Only room for one survivor in this rescue vehicle. Launch: 06/11—06/18/2010
DLC: 07/24/2012—so far
Campaign Finale
As the name implies, only one Survivor is allowed in the rescue vehicle. Teamplay is encouraged "only long enough until you can survive on your own" as the Blog Post states. Instead of beginning at the start of a campaign, this Mutation automatically selects the finale for everyone to start on. The first Survivor to enter the vehicle (and end the campaign) will be listed as "(Name) was the first survivor out!" in the rolling credits.
Headshot! The only shot that counts is the one in the head. Launch: 06/18—06/25/2010
Encore: 11/18—12/02/2011
DLC: 07/24/2012—so far
When using guns or melee weapons, only a headshot or decapitation will kill a Common Infected. Anywhere else merely causes them to stumble. Grenades, Chainsaws, Grenade Launchers, M60s, and the Heavy Machine Gun will affect Common Infected as normal. Special Infected are not subject to this.
Versus Survival
(Survival Versus)
Can you survive against your friends? Launch: 07/02—07/09/2010
Encore (PC): 07/30—08/06/2010
Developer's Choice: 09/24—10/05/2010
Encore: 04/22—05/06/2011
Encore: 06/03—06/17/2011
Encore: 07/15—07/29/2011
Encore: 08/26—09/09/2011
Twitter's Choice: 03/29—04/13/2012
DLC: 07/24/2012—so far
Versus mixed with Survival. Rounds have the teams alternating roles, trying to beat the last record set by the opposition until one team falls short of the record. Favors Infected side due to never ending waves of Common Infected and an enclosed area. This mutation became an official game mode on September 24, 2020 as part of The Last Stand update.
Four Swordsmen
(of the Apocalypse)
Four Swords against plenty of apocalypse! Launch: 07/09—07/16/2010
Encore (Xbox 360): 07/30—08/06/2010
Twitter Choice: 03/16—03/29/2012
DLC: 07/24/2012—so far
The Survivors will start with a Katana in hand from the start; primary weapons and other secondary weapons won't spawn. Common Infected do not spawn; only Special Infected do, albeit at an increased spawn rate. The title is probably a reference to the four horsemen of the Apocalypse.
Hard Eight Double the specials, quadruple the fun! Launch: 07/16—07/23/2010
Developer's Choice: 09/03—09/10/2010
Encore: 12/03—12/17/2010
Encore: 02/03—02/24/2012
DLC: 07/24/2012—so far
The maximum number of Special Infected spawning at the same time has been raised from four to eight. Additionally, the spawning rate of Special Infected has been increased.
Healthpackalypse! No health in this versus game. Launch: 07/23—07/30/2010
Developer's Choice: 09/17—09/24/2010
Encore: 09/23—10/07/2011
DLC: 07/24/2012—so far
As the tagline implies, there will be no first aid kits, pain pills, or Adrenaline Shots in this mode. Survivors must be extremely careful, especially against the human-controlled Special Infected as there is no way to recover health once it is lost. Favors Infected side due to no ability to recover lost health.
Gib Fest Blast infected to shreds with the M60. Launch: 08/06—08/13/2010
Encore (PC): 08/27—09/03/2010
Encore: 11/19—12/03/2010
Encore: 05/20—06/03/2011
Encore: 10/07—10/21/2011
Encore: 01/13—02/03/2012
DLC: 07/24/2012—so far
The Survivors will start with M60s and a Magnum to fend off the Infected. No other primary or secondary weapons will spawn during the game. The M60s will have unlimited ammunition similar to Chainsaw Massacre . Incendiary and explosive ammo are still limited to 150 rounds, after which the M60 reverts to standard ammunition.
Iron Man No respawns, no restarts, no ammo, only tension. Launch: 08/13—08/20/2010
Encore: 10/21—11/04/2011
DLC: 07/24/2012—so far
Once a Survivor dies, they can only come back with a defibrillator, if found, or if the team makes it to the safe room. If all the human Survivors in a team die, they must start all over from the lobby. There are no ammo piles throughout the whole campaign, so the only way to get more ammo is to change your gun. This Mutation is almost the same as Realism (no Survivor or item glows, Common Infected are tougher, etc.), with only the penalty of the game ending when everyone dies instead of restarting the chapter.
Taaannnkk! Every Special Infected in this Versus game is a Tank! Launch: 10/05—10/15/2010
Encore: 11/12—11/19/2010
Encore: 05/06—05/20/2011
Encore: 07/29—08/12/2011
Encore: 02/24—03/16/2012
DLC: 07/24/2012—so far
The Special Infected team will only spawn as Tanks throughout this Mutation. If a Tank dies, the player will respawn as another Tank instead. Survivors get a 15-second head-start, but first aid kits have been replaced by pain pills. This Mutation was revealed on the Left 4 Dead Blog as part of The Sacrifice weekend updates, and activated on a Tuesday instead of Fridays as normal to celebrate the release of The Sacrifice.
Hunting Party Nothing but Hunters on the prowl. Launch: 10/15—10/22/2010
Encore: 06/17—07/01/2011
Encore: 09/09—09/23/2011
DLC: 07/24/2012—so far
The Special Infected in this campaign are only Hunters. Boomers, Smokers, Jockeys, Chargers and Spitters do not spawn. Up to six Hunters can be present at once. Tanks and Witches will still spawn as normal, including specially scripted ones (The Riverbank and The Docks, along with finales).
Lone Gunman You and your Magnum against the deadly horde and Boomers. Launch: 10/22—10/29/2010
Encore: 07/01—07/15/2011
DLC: 07/24/2012—so far
Single Player
You will play by yourself with no Survivor Bots to back you up, and armed with only a Magnum. While other weapons do not spawn, grenades still do. The only Infected are Boomers and the Horde. Tanks and Witches will still spawn as normal, including specially scripted ones. Common and Uncommon Infected have greatly increased damage; each hit from the front will do 15 damage on Easy, 30 damage on Normal, 75 damage on Advanced and instant incapacitation on Expert.
Bleed Out Versus Now you have a good excuse for rushing through Versus. Launch: 10/29—11/05/2010
Encore: 07/15—07/29/2011
DLC: 07/24/2012—so far
Bleed Out Versus is Versus with Bleed Out rules. Survivors will only have temporary health throughout the game, with only Adrenaline Shots and pain pills spawning instead of first aid kits.
Healing Gnome Share the gnome to replenish life. Launch: 11/05—11/12/2010
Encore: 08/12—08/26/2011
DLC: 07/24/2012—so far
Gnome Chompski spawns with the Survivors. All Survivors start with 99 temporary health. No healing items of any kind will spawn. As the only method of healing is to carry Gnome Chompski, Survivors must alternate in carrying the gnome to restore their health.
Special Delivery These specials deliver non-stop action. Launch: 12/17—12/31/2010
DLC: 07/24/2012—so far
A variation of Hard Eight, with the maximum number of Special Infected raised from four to eight. Additionally, the spawn timer of Special Infected has been removed. To offset the larger number of Special Infected, Common Infected along with Uncommon Infected do not spawn. Special Delivery is the first community Mutation officially released for both PC and Xbox 360, created by Rayman1103 from his custom Mutations mod.
Flu Season The smell of bile and spit in the air. Launch: 12/31/2010—01/14/2011
Encore: 05/25—06/14/2012
DLC: 07/24/2012—so far
In this mode, only Boomers and Spitters spawn normally. Common Infected are spawned by the Boomer's bile (if it lands on Survivors) or during Crescendo Events. Tanks and Witches only spawn during scripted events depending on the campaign. Boomer and Spitter spawn timers have been removed and maximum number raised from four to ten. Boomers are much faster and more agile, and do not have cooldown on their bile vomit, while Spitters are also faster and more agile with shorter cooldown on their acid spit. Flu Season is the second community Mutation officially released for both PC and Xbox 360, and is a combination of the works of SR69MMJC and Karma Jockey.
Riding My Survivor Do I hear a Jockey? Launch: 01/14—01/28/2011
DLC: 07/24/2012—so far
Only Jockeys spawn in this mode. Jockeys have increased health, damage, and speed. Riding My Survivor is the third community Mutation officially released for both PC and Xbox 360, created by Winded.
Nightmare You'll never see them coming! Launch: 01/28—02/11/2011
Encore: 06/15—07/10/12
DLC: 07/24/2012—so far
In this mode, Common Infected and Special Infected are stronger. Survivors will be unable to see glows on fellow players or objects. The fog is adjusted to be thicker on all survival levels. Nightmare is the fourth community Mutation officially released for both PC and Xbox 360, inspired by Karma Jockey.
Death's Door You go down, you're dead. Launch: 02/11—02/25/2011
DLC: 07/24/2012—so far
In this mode, incapacitation is disabled. If a Survivor falls, they will die instantly. First aid kits do not spawn; pain pills will spawn where they would normally spawn, such as in safe rooms and finales. Death's Door is the fifth community Mutation officially released for both PC and Xbox, created by Rayman1103.
Confogl For the competitive type. Launch: 11/04—11/18/2011
Encore: 12/02/2011—01/13/2012
Testing: 07/10—07/24/2012
DLC: 07/24/2012—so far
In this mode, players start with pain pills in their inventory, and can find additional pills and adrenaline in each map, but no first aid kits spawn anywhere. In addition, the only primary weapons available are Tier 1 weapons and the Hunting Rifle. Confogl is the sixth community Mutation officially released for both PC and Xbox, created by ProdigySim.
Holdout Custom
In this mode, players will hold out in a certain location until rescue arrives, against multiple waves of zombies. It has two modes: 'Training' and 'Challenge'. In training, you hold out against a certain amount of waves, with a helicopter delivering supplies about halfway through. In challenge, you must fuel a generator to make a timer count down, with the helicopter arriving the wave after it finishes. In holdout, special infected drop 'supplies', which can be used to buy items such as Defibrillators or Tier 2 weapons, as well as custom weapons such as mines.
Dash Custom
In this mode, players must move between different waypoints, with a horde and Specials spawning after each waypoint is activated. Waypoints either are activated by one player, or require all four players to activate.
ShootZones Custom
In this mode, players must stand in specific 'shootzones' (gravestones) in order to deal damage. When in a shootzone, it will play music. After several seconds, the shootzone will be disabled. Only Common Infected spawn in this mode.
L4D1 Coop Campaign
In this mode, only Left 4 Dead weapons, items, Common Infected and Special infected spawn. This means only Smokers, Male Boomers and Hunters, along with Witches and Tanks will spawn as special infected. The weapons that spawn include the Pump Shotgun, Tactical Shotgun and Submachine Gun with their ammo changed to their original amounts, as well as the Assault Rifle and Hunting Rifle, and Pistols as the only secondary weapon available. The only items that spawn are Pipe Bombs, Molotovs, Health Kits and Pills. Map-based items such as Fireworks are unaffected.
L4D1 Versus Versus
Identical to L4D1 Coop, but in Versus instead.
L4D1 Survival DLC: 09/24/2020—so far Survival
Identical to L4D1 Coop, but in Survival instead.
RocketDude DLC: 09/24/2020—so far Campaign
In this mode, there are no bot survivors and the human Survivors have 200 health. They are equipped with a Grenade Launcher with infinite ammo and clip size, and either a sharp melee weapon or a Magnum. The Grenade Launcher's grenades do full damage to infected, but are are modified to act like "rockets" which travel in a straight line and do minimal damage to the user (1-2 damage on Normal) and launch props and players into the air on hit. The aim of this mutation is to spend as much time in the air as possible using the Grenade Launcher, which is kept track of by the game as a percentage once the players reach the Safe House. If the Survivor is downed, they can revive themselves in black and white by killing a Special Infected, though if they are pinned by a Special Infected, they will lose if once the game finishes a 10-second countdown. The only items that spawn are Pain Pills and Adrenaline, though each map features hidden mushroom pickups that act as an instant health pack, give the user the ability to bunnyhop by holding the space button, and give their grenades a flaming trial. Created by Rene™.
Tank Run DLC: 09/24/2020—so far Campaign
Only Tanks spawn in this mode. All weapons (except for the M60) have infinite ammo, pipe bombs explode much faster and will cause Tanks to stumble, bile now slows Tanks significatly and causes them to take rapid damage over time, and ammo piles are replaced with laser sights. Finales will also spawn two Tanks at once, and all finales last 10 minutes, even finales like The Sacrifice. Certain maps, such as The Sacrifice and Last Stand, will spawn 3 to 6 Tanks when the rescue arrives. Created by Rayman1103.

Console Commands[]

To play any Mutation without it being up for that week on the PC version of Left 4 Dead 2, activate the console and type in:

map map filename mutation-name

The map filename is any of the maps in the game, or a custom map.

Replace mutation-name with a command from below:

Command Mutation
mutation1 Last Man On Earth
mutation2 Headshot!
mutation3 Bleed Out
mutation4 Hard Eight
mutation5 Four Swordsmen
mutation6 Nothing
mutation7 Chainsaw Massacre
mutation8 Ironman
mutation9 Last Gnome On Earth
mutation10 Room For One
mutation11 Healthpackalypse!
mutation12 Realism Versus
mutation13 Follow the Liter
mutation14 Gib Fest
mutation15 Versus Survival
mutation16 Hunting Party
mutation17 Lone Gunman
mutation18 Bleed Out Versus
mutation19 Taaannnkk!
mutation20 Healing Gnome
community1 Special Delivery
community2 Flu Season
community3 Riding My Survivor
community4 Nightmare
community5 Death's Door
community6 Confogl
dash Dash
l4d1coop Left 4 Dead 1 Coop
l4d1vs Left 4 Dead 1 Versus
l4d1survival Left 4 Dead 1 Survival
gunbrain GunBrain
holdout Holdout
shootzones Shootzones
tankrun Tank Run
rocketdude RocketDude

So, for example, to play Dead Center with the Ironman Mutation, type into the console:

map c1m1_hotel mutation8

A menu mod exists that simplifies this, as well as enabling lobbies.[1]

Note: You cannot play multiplayer using this method.

Unrevealed Mutations[]

Future content.png "Ain't seen anything like this before..."
This article contains new or upcoming content, and therefore may be incorrect and will change from time to time.

WARNING: Spoilers.

The following were found in a Steam-Group announcement and have not been seen in a schedule as of yet. They can also be found amongst the game's script files. As they have not been announced by Valve yet, they may still be subject to changes or removal.

Mutation Tagline Mode(s)
The Last Samurai Alone, armed only with a sword, you venture forth. Single Player
You are alone with no Bots to back you up, similar to Last Man On Earth. However, you will only be armed with a Katana. Common Infected do not spawn; only Special Infected do.
Ultra Realism The ultimate realistic challenge. Realism
There is/are no HUD or outlines around to help you here. Enemy Infected changes are unknown, but may have more resistance to gunfire similar to normal Realism.
VIP Target Unknown Versus
Last Gnome on Earth mixed with Versus. The Survivors start with Gnome Chompski nearby and must transport it to each safe room and into the rescue vehicle during the finale. Favors Infected side due to Common Infected constantly harassing the gnome carrier who cannot use weapons while carrying, effectively putting one Survivor out of play.


Realism Versus[]


As Survivors
In general, as Survivors, you're going to have a hard time. If possible, try not to plan out your route through the level before you leave the safe area. The fewer decisions you have to make on the fly, the better you will do. Also be aware that the pistols will be ineffective unless you constantly headshot, so bear that in mind when deciding between a pistol. However, the Magnum still one-shot kills Commons on any part of their body, and also a decent ranged shooter.
Once you are on the move, keep moving. Always be aware of whether or not the Infected are spawned, and which ones are spawned. Use sound cues to your advantage. While saving a downed Survivor is extremely risky, always judge whether you should do it based on what Infected are spawned. You can't afford to lose a second player trying to save the first. This game has a lot to do with who knows how to keep on the move while still employing proper team tactics, and not separating. Stay together, move quick.
Using microphones is a good idea, as even Valve suggested in the in-game Blog Post for Survivors of Realism Versus to use them to communicate faster. Typing in Realism Versus is almost suicidal.
If you are pinned anywhere, QUICKLY communicate to your team where you are and any other Infected that are near you. A great way to do this is using an aerial position marker where possible, because it means even people who don't know the map can find you based on visuals. (An example would be "Help! I'm pounced under the Jazz sign up the stairs, and there's a Smoker nearby me.") If this is not possible, either because you are indoors or there are actually no landmarks around you, try your best to direct your team to you by saying either "behind, left, right, or in front". Assume they're facing forwards unless you can visibly see them looking a different direction.

As Infected
Going in, realize that you have an immense advantage, especially if all players are human, however for competitive play you still want to disable the enemy team as quickly as possible to give yourself an easier time as Survivors.
Even more so than in a typical Versus game, separating the Survivors is key. To do this you want to use each of the Infected to the best of their ability while remaining out of sight of the Survivors where possible. Always keep in mind that you don't need to Survive, the Survivors do. Working with your team to do a huge hit and then dying is significantly more effective than Surviving for a long period of time and making the odd attack on your own. The following list is a slightly modified variation of how to best play each Infected, fit for Realism Versus.

The Jockey
The Jockey is one of the most powerful Infected in Realism Versus. Using the Jockey's capabilities to steer people away from the pack is an extremely simple thing to do, too. Get a teammate to provide a distraction, then grab the Survivor furthest to the back and haul them backwards, keeping in mind as soon as you get out of visible range of the Survivors your job will be much simpler. A distraction should be something that puts the Survivors in a sense of overwhelming urgency. A Hunter pouncing someone does this job, especially if the pounce was a high damage pounce. A Smoker pull into a car alarm is another great example, and as always there's the reliable Boomer horde. Use them to your advantage. A lone Jockey is a dead Jockey.

The Smoker
The Smoker is another extremely powerful weapon in Realism Versus, as it also has the ability to get Survivors off their planned course and out of sight. A Smoker should also attempt to use any distraction to pull a Survivor out of sight. Also, as Smoker, use ledges, alarmed cars, and Witches to your advantage. If you are working together with a Jockey, you should realize that since you can both do higher damage and can attack from further away, you should be attacking first, providing a distraction for the Jockey to get in and get out. Try not to pull directly into the path of where the Jockey should go, and as always, never pull the Survivors forwards (unless it is over a ledge, into an alarmed car, or a Witch.)

The Hunter
The Hunter, in Realism Versus, wants to be as stealthy as possible. While you have ridiculously loud screams, you can still pounce from far away essentially muting them. With no warnings to the Survivors other than each other, they don't need to know you are in the midst of them. Not necessarily going for extremely high damage pounces, but going for mid-damage pounces (in the 10-20 range) and landing on the rear-most Survivor in a group is a great way to do damage. The reason you shouldn't always go for extremely high damage pounces is because they are both predictable, and if you miss it's very obvious that there's a Hunter in the midst of the Survivors. You are a distracting Infected. Not in the same sense a Boomer is, but you are extremely powerful and one of the most urgent Infected to kill. As such, combine your attacks with the Jockey, Smoker, and Charger for maximum effectiveness.

The Charger
The Charger, as always, is an extremely dangerous Infected. Your ability to do mass amounts of damage, send the team flying, and go off ledges with Survivors is something that is unrivaled by all the other Infected. You should attack mostly as you normally would, but bear in mind that you are a massive distraction and stealth won't really be an option. Destruction is the name of the game as a Charger, and you should keep that in mind. Attack first where possible, providing a separated, confused, and damaged Survivor team, so the other members of the Infected team have an easy time picking people off.

The Boomer
The Boomer, as always, is here to distract. Covering Survivors in bile is extremely effective in Realism Versus, for two reasons. Firstly, it's hard to see if your teammates are covered or not, and secondly when Survivors already lose all outlines, the ability to blind them further is a much needed hindrance when you're destroying the team. Use it as you always would, around corners, jumping off roofs, basically get into the middle of the Survivors and go for as many as you can.

The Spitter
The Spitter is a high damage, low mercy Infected individual. Your job doesn't change a whole lot, get Survivors out of corners (which they will be in, in this game mode.) and add extra damage to a confusion filled mess. Spitting on a pounced, smoked, or charged Survivor is a great way to do some extra damage and slow down the Survivor recovery process. Your job will not change dramatically due to the new game mode, so just use the Spitter intelligently and it will do wonders for you.

The Tank
The Tank, in Realism Versus, means the end. Very rarely will you face a team that can take down your entire team and a Tank while in Realism Versus mode. However, due to Infected error, it can be somewhat common that a team may survive past the Tank. Your team must attack with you. If you need to wait and throw rocks until your entire team is ready to spawn, do so. Do not rush in alone, unless you're completely confident that waiting a maximum of 25 seconds would put the Survivors in too good a position for you to allow. (For example, if they're currently inside and if you wait 25 seconds they will get into a flat, open parking lot.) Use your team to slow down the Survivors, and then get in there and attack the Survivors. As always, use cars and other objects to your advantage where ever possible.
You are not the lone warrior that can destroy the Survivor team. Do not think you are. You are an extremely powerful teammate, as a Tank, and you need to treat yourself like an equal member of the team for your Tank attack to be successful. More than anything, never attack a teammate in an attempt to do more damage as a Tank, and never hit a pinning Infected off a Survivor, as more often than not you send the Survivor flying as well, which can give them an escape route they wouldn't originally have.

Bleed Out[]

  • In this Mutation, the Survivors do not have permanent health. Once they load up, they will have 100 temporary health, which will tick down slowly, but surely. first aid kits will never spawn; only pain pills and Adrenaline. Survivors must keep moving; should their health fall to 39 or lower, they will move slower, allowing the Tank to outrun them. Reaching 1 health will result in an even slower speed and be vulnerable to any attack.
  • As a result of temporary health, there may not be enough time to explore rooms for supplies. Judge on the amount of health yourself and other Survivors have before considering doing quick searches.
  • In this Mutation, hordes will be constant - you will constantly hear the screams of distant Infected signifying an incoming horde attack. Taking melee weapons may be preferred due to dealing with multiple Common Infected. Special Infected will spawn at around double the rate too; they may appear at moments which are usually quiet in normal Campaign.
  • Using headsets may be a viable choice, if not in a team which can work by picking up each others' cues, as typing will take time, and thus, health dropping.
  • Moving in a formation together with the hardiest Survivor at the front taking point, as they will be the first into rooms to watch out for Special Infected. If the point Survivor is pinned the other three will be close by, shooting the Infected. The Survivor on point will most likely be very damaged because of the temporary health, so they will use their pills (or someone else's, if players want to keep that Survivor on point duty, the lineup can be changed along the way). But don't forget, the other Survivors' health will be ticking down, too, so the back Survivor will look behind them for pills and adrenaline. If found, that Survivor will inform the others. The middle two Survivors will have the easiest job, killing all of the stray Common Infected, or Special Infected. If everyone stays together, if one gets pinned the others can save them. This may be a very common tactic for most, if not all game modes, but may be effective for this Mutation in particular.
  • Weapon choices will be based on repeatedly dealing with multiple Common Infected throughout the campaign. Melee weapons, Shotgun variants, and Assault Rifle variants will be the general weapon of choice in this mode. Weapons such as the Magnum and the Hunting and Sniper Rifle may prove to be alternative choices, as they can pierce multiple Common Infected with a single shot, and in this Mutation, the chances of this happening will be extremely high.
  • Make use of shoving; you will be on the move, and shoving Infected stuns them briefly to either run past or shoot them on the move.

Follow the Liter[]

  • One good way to speed up the can collection process is to have one couple of players carry one can to the generator/car and have another pair seek out another can and grab it as soon as the other can has been put in. This effectively cuts the search time in half while keeping issues to a minimum. One downside to this method is that two Infected could take out both Survivors in one party when another team is far away.
  • If playing against a low number of players you could stockpile the gas cans, with at least one person protecting them, until there is a player-controlled Spitter. At that time it is advised to start putting them into the generator.
  • Oddly, but obvious enough, one very effective strategy is to "follow the leader" and stick together in one big group having the three non-carrying Survivors shoot down the incoming Infected.

Last Gnome on Earth[]

  • In this Mutation, Common Infected will chase the Survivor holding onto Gnome Chompski as if he was splashed with Boomer bile. If dropped, Common Infected revert back to their normal behavior until someone picks up the gnome again. This can be used to lure Common Infected towards a specific point at times.
    • If one of the Survivors who are not holding Gnome Chompski is splashed by a Boomer, Common Infected will attack that Survivor even if someone else is holding onto the gnome.
    • Bile bombs and pipe bombs will lure away the Infected if a Survivor is carrying Gnome Chompski.
  • During this Mutation, Gnome Chompski cannot be thrown, only dropped. This is probably to prevent shortcuts on various maps, and accidentally throwing it into an unreachable or deadly area.
  • Gnome Chompski will go flying if hit by a Boomer exploding, a Grenade Launcher, or other explosions. If this happens, the gnome may land in an unreachable area, forcing the Survivors to manually restart the chapter or campaign.
  • The Survivor carrying Gnome Chompski will be attacked by all Common and Uncommon Infected. Do not run off leaving them on their own, as the gnome is required to complete the campaign! Ideally, the Survivors should all stick together.
  • If in a full team of human players, forming a triangle formation (with the Survivor carrying Gnome Chompski in the middle of the triangle) during movement may be a good idea, as the three non-carrying Survivors can fend off the Infected from all sides on the move while the gnome carrier can run unhindered.
  • Special Infected are not affected by the presence of Gnome Chompski. Just because you're not the gnome carrier, do not think that Smoker will ignore you!
  • Be careful not to leave Gnome Chompski at a point of no return. As Survivors will be unable to return to pick up the gnome, the chapter they are on cannot be completed and must be manually restarted.
  • Gnome Chompski must be inside a safe room, and carried by a Survivor for the chapter to end. Leaving the gnome outside and closing the door will not end the chapter.
    • Gnome Chompski must also be carried into the rescue vehicle. If the gnome is not in the rescue vehicle despite all alive and non-incapacitated Survivors being on board, it will not take off! The gnome must also be in the arms of a Survivor in the rescue vehicle; leaving it on the floor of the rescue vehicle is no good either!
  • When dealing with hordes or a Tank, it may be prudent to drop Gnome Chompski to deal with the Infected before picking up the gnome and moving on.
  • On finales, dropping Gnome Chompski near a defending point or near the rescue vehicle location is probably the best way to deal with the gnome without worrying about it during the waves and Tanks. Watch out for any Boomers exploding or other explosions which may knock Gnome Chompski into an unreachable area!
    • Another option, during defensible finales such as houses, is to stash Gnome in a closed-off area such as a closet.
  • Alternatively, as Common Infected behavior is affected by Gnome Chompski, having one Survivor carrying the gnome can lead the Common Infected into a defined path for the other three Survivors to deal with without being attacked by them. Although Special Infected will be unaffected by this tactic, it may prove handy in some scenarios, such as in The Passing, with Francis, Louis and Zoey to protect the gnome carrier while the other three Survivors collect gas cans.
  • Due to the fact that Gnome Chompski is movable by shooting it, unscrupulous players may attempt to grief the team by shooting the gnome into an unreachable place.
    • The gnome can be retrieved by a pipe bomb, but in The Passing, when passing through the pipes, the fence behind the two dumpsters has passable corners for the gnome, meaning it can slide in and being ultimately unreachable.

Last Man on Earth[]

  • In this Mutation, you will have no help from fellow Survivor Bots. However, there are no Common Infected. Nevertheless, you are still in danger from all Special Infected, excluding the Boomer who does not appear in this Mutation due to the fact that no Common Infected around defeats the purpose of a Boomer puking on you. (A Boomer may, however, still spawn in the Safe Room following the crescendo event in The Church.)
    • As you are the last Survivor, this means Zoey, Francis, and Louis do not appear in The Passing at all. Some other Survivors, such as Virgil, may not have any dialogue either during this Mutation (excluding communication in finales).
    • Even though this Mutation has no Common Infected, there will still be some of them during the cutscene in Dead Center when you crash out of The Atrium with the car. However, this will have no effect on gameplay at all. Common Infected may also be triggered to spawn in places such as Dead Center's Opening sequence when 2 Common Infected run out of an apartment on fire, or in The Passing when the Tour Bus runs over one. Despite the fact you never killed them, it will still account for them in the Credits.
  • Tier 2 weapons will spawn much earlier than normal during this Mutation.
    • In the absence of a Tier 1 or Tier 2 weapon, dual Pistols should be avoided unless absolutely necessary, as the absence of accuracy and damage is risky around two or more Special Infected.
  • Molotovs are generally more useful than other throwable weapons as it can help take down a Tank solo and can burn a pinning Infected to death before they can incapacitate you. Pipe bombs do spawn, but are of little use seeing as the Special Infected do not chase them. Bile bombs still spawn as it can be used to turn the Special Infected against each other, excluding the Tank and Witch, as well as giving them a visible outline, which can be very useful against the former.
  • Chainsaws are extremely valuable in this Mutation and are not too difficult to find without the Common Infected around. It can save you from a Smoker's tongue and kill most of the Special Infected, including the Tank, within seconds. Aiming up high while holding down the attack button will also kill a Jockey or Hunter mid-pounce. Due to the fact that no Common Infected are around, running out of gas is rarely a problem.
    • In the absence of a Chainsaw, a standard melee weapon can also save you from the Smoker's tongue attack, but it requires very precise timing along with knowing which direction the tongue is coming from. You must hit the tongue just BEFORE it attaches onto you. If done correctly, the tongue will be ruined, allowing you to quickly deal with the Smoker in question who is now vulnerable to attack, or to run away before the Smoker's tongue attack recharges.
  • There are many first aid kits scattered around, so if necessary, backtrack to get one if previously caught by a Special Infected.
  • Special Infected generally appear in groups of one, two, or three. There are generally never four or more together.
  • Keep your eyes peeled for Smokers, Jockeys, Hunters and Chargers especially as they have the ability to take all your health down if they manage to grab you. However, they will release you when you reach zero health, and you will immediately stand back up (see note below).
  • Spare any Spitters that may appear during the chapter run. They are the least dangerous Special Infected, as it's easy to avoid their spit attack. By leaving them alive, you also ensure that one of the Special Infected slots are filled and can prevent a more dangerous Special Infected, like a Smoker, from appearing. You should kill them though if they attempt to claw you, as it can deal considerable damage on higher difficulties and you will not be revived if you are incapacitated via clawing.
  • When health is depleted to zero from being grabbed, instead of being incapacitated, the Survivor is revived immediately and the view becomes colorblind, indicating that using a first aid kit is necessary as the next knockdown means death.
  • When you revive from getting pinned, it may be a good idea to use an Adrenaline Shot since you can run at full speed and heal yourself faster.
  • When a Special Infected who has you pinned downs your health to zero the first time, The Director may lower all Special Infected aggression temporarily. What this means is that if you are downed by a Charger for example, and there is a Hunter nearby, both may retreat to give you some time to regroup. Be advised, however, as they will come back before you can heal, so make sure to use pain pills or Adrenaline for a temporary fix until they're dead before healing up.
    • In case of Chargers, the Director will always force them to back up after you have been incapacitated.
    • Hunters may occasionally run away, but it is not uncommon for one to keep slashing at you after pinning you so make sure to push and shoot him before trying to heal.
    • Smokers naturally flee as this is part of their AI coding so there is no difference there.
    • Jockeys rarely flee and either keep slashing at you when they down you, or stand still for a couple of seconds after another Special Infected has downed you before resuming their attack on you.
    • Spitters, like Smokers, flee naturally due to their AI coding.
    • Tanks, however, never retreat. However, getting downed by a Charger, Hunter, or Smoker gives you temporary invincibility to damage while your character is getting back up or knocked away by a Tank's punch. Move away ASAP while using a temporary healing item and do what it takes to defeat the opposition.
  • There are situations where you can be incapacitated and it will be immediately game over:
    • A Tank indirectly hitting the player with punchable objects.
    • Getting incapacitated by a Witch.
    • Getting incapacitated by a Spitter's acid pool.
    • Falling from a high ledge (whether by dangling and dropping or just jumping).
    • Getting clawed by a Special Infected (as it does not pin, the revive mechanic does not apply)
  • Use your surroundings to aid blocking the Infected's view of you. The Smoker cannot grab you if you're hiding behind a wall, for example. Try not to put yourself into a position where a Charger can easily rush you, such as narrow passageways until it is necessary. Chargers and Jockeys can be fought in large open areas with scoped weapons. Jockeys because they must get close to you to attack in which by then, you will have dealt heavy damage to them and Chargers because it is much easier to dodge their charging attack. Fight Hunters and Smokers in enclosed areas with shotguns. Hunters because you can camp by the doorway until you see them crawl through it, then push them back and finish them and Smokers because you can stand back from the doorway until they step through and then shoot them. Keeping back from the doorway means if a Smoker does catch you out, you still have time to react before it immobilizes you, unlike standing by the doorway.
  • If the Jockey grabs you, it will do as much damage as the other Special Infected who are able to grab Survivors. This is presumably so you will be downed faster and get back into play quicker. On the plus side, you may be able to avoid being steered into Witches as a result due to being downed faster.
  • Tanks do half the damage they normally would in Campaign. This means on Expert, a Tank will be unable to instantly incapacitate you if you have more than 50 health at the point it hits you with a melee attack or a rock. This won't apply if you get struck by an object the Tank punched, however.
  • Sometimes, the best way to deal with a Tank is to run past him lighting up the path with gas cans and a Molotov on the way. However, if you are forced to fight, always run around taking cover when the Tank starts throwing objects at you while you continue to fire at him. If you have it, use a Molotov or gas can to light the Tank on fire and stagger him with a propane tank. At the same time, look for any other Special Infected around to make sure you don't get pinned in the process since you have no time to heal yourself.
  • As you are on your own during this Mutation with no Survivor Bots or Common Infected to slow you down, grabbing some Achievements may be much easier than normal:
    • During Sugar Mill in Hard Rain, as you are on your own, it is fairly simple to run past all the Witches without them being startled, in order to get SOB STORY, once you reach the safe room. The only problem lies in the Tank, which may make an appearance on this stage. It is possible to down the Tank yourself with a combination of gunfire, maneuvering and possibly a Molotov to help slow down the Tank as well as constantly damaging him, but be mindful of your surroundings as if a Witch dies due to either yourself or the Tank's doing, you will not get the achievement.
    • During The Bridge in The Parish, it is easy to get BRIDGE OVER TREBLED SLAUGHTER, as long as you keep moving, and avoid the Tank. Remember to grab an Adrenaline Shot to get past the Tank more easily. There are no Common Infected to slow you down, so adjust weaponry accordingly. As only a limited amount of Special Infected spawn at once and the fact that the first set appears behind the player, running away from them as fast as possible without any of them dying will result in a fairly smooth ride as no Special Infected will spawn near you.
    • It is also easier to get TANK BURGER, since there are no bots to shoot the Tank, and no Common Infected around. Just hitting the Tank once with a melee weapon in any finale, and rushing to the rescue vehicle will earn you the achievement due to the Tank lacking human players to pass control to.
    • LEVEL A CHARGE is also considerably easier to get in this Mutation, since there are no Common Infected or Survivor Bots to ruin your chances against the Charger. Damage the Charger with your gun, as well as finishing any other Special Infected if any, and wait for it to charge you before attempting to hit it with a melee weapon.
    • STILL SOMETHING TO PROVE is another achievement that can be attained due to no Common Infected around to stop you. Keep on the move and save the Molotov for the Tank whenever they appear.
    • THE QUICK AND THE DEAD can be acquired very easily, even without any Survivor Bots. If you are incapacitated by a Special Infected that puts you in black and white (Hunters, Smokers, etc.) while under the speed-boosting effects of adrenaline, it counts as "picking up" an incapacitated teammate and counts towards the achievement.

Chainsaw Massacre[]

  • In this Mutation, all you have to pick between is the Pistol or Chainsaw. While both have their obvious pros and cons, for a more balanced team, one Survivor should ideally keep their Pistol, and pick another from the ground to dual-wield, in order to deal with targets such as Spitters and Boomers, who are normally dangerous to attack at close range.
    • For a more fun and frantic game, everyone should pick Chainsaws! Many normal campaign tactics go out of the window!
  • While Survivor Bots will never grab a chainsaw (and will swap it out for pistols if they have the chance), for this particular Mutation, they will immediately pick it up and use it as much as they can. As per standard for Survivor Bots, they will not inflict friendly fire damage on each other or human players, though human player screens will still react as if they were attacked.
    • Survivor Bots are hesitant to attack Boomers due to their coding working against them, as they will continually shove the Boomer until it explodes. Human players should kill them afar with pistols before they can bile anyone.
    • Again, with their coding working against them, Survivor Bots are also hesitant to attack Witches if they are passive. However, their Chainsaw AI (which forces them to run into melee combat) will force them to run right up to the Witch in question, and wait for her to get angry enough, upon which, they will then attempt to attack, but by then, it may be too late for one of the Survivor Bots who has just been incapacitated or killed by the Witch. Occasionally, they may kill the Witch before she attacks, but this is rare. Players will have to kill the Witch themselves if they want to keep Survivor Bots on their feet.
  • If incapacitated while wielding a Chainsaw, Survivors will have access to a Pistol until helped back up on their feet, upon which they will only have access to the Chainsaw as before.
  • When dealing with Smokers, the Chainsaw can free you if attacked by tongue, as you are starting to be dragged. Once fully dragged (the view changing to show the Survivor being dragged as they are struggling to pull the tongue off themself) it is no longer possible to use the Chainsaw to free yourself.
  • Go easy on the Chainsaw when freeing other Survivors who have been pinned by Special Infected such as the Hunter or Jockey, as the Chainsaw is very easy at inflicting friendly fire damage. It may be preferable to shove the Special Infected off the Survivor before finishing it off. Unless the Special Infected is a Charger, in which case a Chainsaw is the only way to free them, besides Pistols.
  • In a team of human players, friendly fire with the Chainsaw is a problem, especially at higher difficulties. Adjust your group formation so that you are not too close together. It may be preferably to move in groups of twos, to minimize friendly fire.
  • The TANK BURGER achievement is easily unlockable during this Mutation, providing that everyone uses Chainsaws against the Tank, which is more likely when working with Bots. This is made even easier with the release of The Sacrifice, as there is a guaranteed Tank Spawn and you can set up the bots right next to the Tank, who will then quickly take him out.
  • When playing with Bots, they will notably struggle to pass through the Crescendo Events or the finale due their aggressive AI and focus more on killing all hordes rather than helping Survivors or escaping. If they see an enemy in sight, they will either stand still or rushing and shed them to death while ignoring incapacitated players. Because of this, it recommended to have at least two human players in the server to be effective cutting through the campaign.

Room for One[]

  • In this Mutation, the first Survivor inside the rescue vehicle in the finale wins! However, you still have to survive long enough for the rescue cue, so don't start backstabbing each other just yet! Work together to ensure survival first.
  • Note that backstabbing your teammates is not the only necessity to winning in this mutation; timing and skill are essential too. For example, slipping away whilst the other Survivors are busy with the penultimate Tank(s) may be incredibly risky, but can give you a head start before the friendly-fire begins.
  • A dangerous but useful technique to kill a Tank is to place yourself between the Tank and a downed Survivor; due to minor glitching, careful positioning will make the Tank strike the downed Survivor as opposed to you, allowing you to kill a Tank at the expense of a future backstabber's health or life.
  • Note that weapon choice can greatly influence the outcome of the match; whilst a shotgun will down a close Survivor in moments, a rifle still has the power to dispatch easily over distances the shotgun cannot reach.
  • It may seem obvious to opt for Adrenaline over pain pills, but one way to get a boost over the other Survivors is to abuse the Adrenaline; if you're subtle (and the others don't have subtitles enabled), you should have an easy time taking all but one shot, leaving you the only one with a speed boost, giving you the upper hand. You may have to briefly switch for pain pills if you want a brief health boost, as taking the last shot means you have the same probability of escape again.


  • In this Mutation, only headshots count against the Common Infected. Although you can shoot any other area of a Common Infected to stun them, they can only be killed by a headshot from a gun. If using a melee weapon, they must be either decapitated or have their head destroyed.
  • Molotovs, pipe bombs, along with gas cans, propane tanks, and oxygen tanks still kill the Common Infected. Fireworks, if available, will also work.
  • Grenade Launchers, M60s, Chainsaws, and the Heavy Machine Gun are still capable of killing Common Infected regardless of area.
  • Make use of the crouch button if using a rifle for more accurate aiming, if you are not surrounded.
  • A melee weapon will have an advantage in this Mutation, as it is considerably easier to repeatedly decapitate Common Infected with a melee weapon than firing headshot after headshot. Remember to aim at their necks or heads!
  • Shoving Common Infected before attacking (if up close) can prove helpful if they move too fast for you to aim properly.
  • The Hunting Rifle and Sniper Rifle are highly recommended as it is usually hard to obtain headshots with assault rifles/shotguns reasonably, especially if you are getting swarmed.
  • Staying together is even more of a necessity, as it will be harder to fight your way through the Common Infected if a Survivor who ventured away from the team is incapacitated and requires help.
  • Survivor Bots have a small advantage in this Mutation, as they are naturally good shots, who generally attempt to aim for headshots regardless of gameplay mode. They can still be swarmed in panic events however.

Versus Survival[]

  • Apply the same tactics as in Survival, finding the best spot to hold off in. Make sure to account for player-controlled Infected, since they'll obviously use different methods to attack the Survivors.

Four Swordsmen[]

  • In this Mutation, you will only have access to the Katana. Unlike Chainsaw Massacre, all Survivors start with a Katana in hand instead of the Pistol, with the weapons lying around. There are also no Common Infected. Nevertheless, you are still in danger from all Special Infected, including the Boomer (unlike Chainsaw Massacre), who spawn at an increased rate.
  • Throwable weapons such as the Molotov and bile bomb still spawn. The pipe bomb will have somewhat limited use, as Common Infected do not spawn, and Special Infected are not affected by the pipe bomb beep. While the bile bomb is just as useless (perhaps even more so, as it does not do any damage with an explosion), it can be used to frighten Witches away if used on them from a distance.
  • Although the Boomer does not spawn Common Infected after successfully covering Survivors in bile, Survivors will nevertheless be unable to see their surroundings, and are more vulnerable to the other Special Infected. As Survivors will only have access to the Katana (no Pistols!), someone will HAVE to go kill the Boomer if they do not want the Boomer chasing them forever. If someone has a Molotov however, they can attempt to set the Boomer on fire and let the flames kill the Boomer.
    • On the other hand, if the Survivors are moving quick, they may opt to leave the Boomer alive as it takes up a Special Infected 'spawn slot', meaning a more dangerous Special Infected such as the Smoker or Charger may not be around.
    • Survivor Bots are hesitant to attack Boomers due to their coding working against them (attack the Boomer only if outside the explosion radius). They will only shove the Boomer away from them if it approaches them. Players will have to step up and kill the Boomers themselves (and deal with being splashed) if they do not want the Boomers to paw the Survivor Bots to death. On the other hand, Survivor Bots do not care about being covered in bile and can still attack with accuracy even if blinded against other Special Infected.
  • Witches have a large advantage in this mode, as the Katana is not able to cr0wn them. Human players will have to either time their swipes to all hit at the same time in order to kill the Witch before she retaliates against the first person to hit her. A more easier choice is to simply run by her and avoid her altogether.
    • Again, with their coding working against them, Survivor Bots are also hesitant to attack Witches if they are passive. However, their Katana AI (which forces them to run into melee combat) will force them to run right up to the Witch in question, and wait for her to get angry enough, upon which, they will then attempt to attack, but by then, it may be too late for one of the Survivor Bots who has just been incapacitated or killed by the Witch. Occasionally, they may kill the Witch before she attacks, but this is rare. Players will have to kill the Witch themselves somehow if they want to keep Survivor Bots on their feet. On the other hand, it may be safer to sacrifice one Survivor Bot to the Witch.
    • Other tactics to kill a Witch in this Mutation include using a Molotov to light her on fire, run away and hopefully let her die from the fire before she reaches the Survivors. A bile bomb, if used from a long distance, can frighten the Witch into running away, although she may turn up later again on the same level.
  • If incapacitated, Survivors will have access to a Pistol until helped back up on their feet, upon which they will only have access to the Katana.
  • Smokers are problematic at long range, as unlike the Chainsaw in Chainsaw Massacre, the Katana can only cut the tongue of the Smoker just before it hits the Survivor with extreme timing and aiming, and knowledge of which direction the tongue is coming from. Stay together and immediately melee shove or attack the Survivor who has been caught to free them.
  • Hunters can be deadstopped (melee shove them in mid air as they leap towards you) which will stun them momentarily and set them up for a quick kill with a swipe from the Katana. Jockeys are harder to deadstop, so move backwards as you see them leap before shoving them to stun, followed by a swing from the katana to kill them.
  • The Tank may be the most horrific enemy of all when faced with only a Katana. As Molotovs still spawn, Survivors may wish to ignite him and run for it, as the Tank's speed will be decreased by the flames. This may not work if Survivor Bots are on the team, as they will bravely face up to the challenge and attempt to kill the Tank even if armed with a Katana. If this happens, and you chose to join in, attack the Tank from his back if possible.
  • Special Infected spawn earlier than normal and at an accelerated rate. This may cause some unusual problems (see below).
    • In The Passing, at The Port, the Special Infected will start spawning as soon as the Survivors leave the safe room. This means the Survivors are in danger before they even start talking to the original Survivors. Incidentally, Louis still has access to the Heavy Machine Gun, while Francis and Zoey will only be armed with a single Pistol. If the three see any Special Infected in their range before the Survivors have activated the lift down to where the generator is, all three will immediately draw Pistols out to shoot them. Bill's body will not have his Assault Rifle next to him.

Hard Eight[]

  • In this Mutation, the normal cap of four Special Infected at any one time has been raised to eight. In addition, the spawn rate of Special Infected has also been raised greatly. Often when the Director spawns a group of Special Infected, you can expect three to six of them in each group.
    • The possibility of double Special Infected (which is an oversight in most Campaigns played normally) can occur anytime during the Mutation.
    • It is possible for an entire team to be incapacitated in one go, especially if the Director spawns only pinning Infected in that group. Be extremely cautious and be prepared to save your allies.
  • Keep moving! Just because you killed the Special Infected doesn't mean that they'll stop spawning.
  • At the start of each level, you may want to cover as much ground as possible. Often when Special Infected spawn, it will be very hard to push through them, especially on higher difficulties.
  • Common Infected are the same as usual in a normal Campaign. Due to the increased spawn cap and rate of Special Infected, panic and crescendo events should be dealt with extreme caution, as teams can be quickly overwhelmed by sheer numbers.
  • Tanks should be dealt with carefully in this Mutation. During a Tank fight, as long as players do not try to run past him to progress deeper in the map, no Special Infected will spawn. As such, never outrun a Tank (apart from the Bridge finale), as doing so will result in a group of Special Infected appearing and they may delay the team to allow the Tank to catch up.
    • Be prepared to deal with Special Infected once the Tank dies, as they'll start spawning after his death.

Special Delivery[]

  • This mutation is similar to Hard Eight, except the Common Infected are no longer present to impede the team. This means that the threat of Boomers has been significantly reduced, as their bile is only dangerous against incapacitated Survivors. However, Special Infected spawn at an increased rate with no cooldown. This means that once a Survivor leaves the safe room, they will immediately start to spawn. Like in Hard Eight, it is mandatory to stick together, and abandon incapacitated Survivors if necessary.
    • As no Common/Uncommon Infected exist, alarmed cars and jukeboxes (on Re:Your Brains) do not trigger hordes.
    • Be wary during a Tank fight, as the team will often need to fight Special Infected at the same time.
  • Players will always start off with a Magnum, though it can be exchanged for regular pistols or melee weapons.
    • Because of the increased presence of Special Infected, the Magnum should never be swapped out for an standard pistol or melee weapon. The only exception to this is the Chainsaw, as it can save the player from most of the Special Infected. The lack of enemies also means that your Chainsaw should not run out of gas.
  • Molotovs and bile bombs can appear in this Mutation; as there are no Common/Uncommon Infected, pipe bombs do not make an appearance. Molotovs should take higher priority over bile bombs as they do little to hamper the Special Infected.
  • Tanks and Witches can spawn in a manner similar to those in Versus.


  • All you really need to do are stick together and watch out for Smokers, Hunters, and any other Infected that is able to inflict damage to you and can only be removed by another Survivor. It is recommended to avoid Witches at all costs (except if your team has chainsaws to kill her instantly or shotguns to cr0wn her). Boomers can be very dangerous in finales or Crescendo Events, and Spitters can be very dangerous against stationary and cornered Survivors. Tanks are possibly the epitome of death in this mutation.

Gib Fest[]

  • In this Mutation, you will only have access to the M60 and a Magnum. While ammo piles exist, they will be useless as the M60 cannot be refilled by ammo piles - not that it makes much of a difference, as in this Mutation, the Survivors' main weapon has infinite ammo. Other guns and melee weapons do not spawn in this Mutation. This will also include places like Whitaker's Gun Shop, which will be devoid of all guns, only having the ammo piles and laser sight.
  • Taking Incendiary ammo or Explosive ammo will upgrade the next 150 bullets (which will be shown by the decreasing amount of bullets left in the M60 every time the gun is fired), after which, the M60 will revert back to 150 unlimited bullets.
    • Notice that if you take another ammunition upgrade before using up the previous ones, you will not get any extra upgraded bullets, but just change the old upgraded bullets. For example, if you have 50 fire bullets, and you use an Explosive ammunition upgrade, you will only lose all fire bullets and get 50 frag bullets. It is advised to use or waste the remaining upgraded bullets before using new ammunition upgrades.
    • Remember that using Explosive ammunition up close can cause friendly fire damage to yourself and your teammates if they are too close to where the bullets impact. Survivor Bots, as usual, cannot cause friendly fire damage unless they accidentally shoot something like a propane tank.
  • Despite the M60 having unlimited ammunition, the trigger should not be held constantly (unless you are going for the "TIL IT GOES CLICK" achievement). It is still advised to use it just like using normal automatic weapons in normal campaigns. Aim quickly but carefully, fire in single shots or bursts. This helps you avoid friendly fire and increases accuracy at long range. Only use full automatic when fighting hordes, Tanks, Witches, and Chargers.
  • Remember to shove if Common Infected get too close, and move your position so that other Survivors are not behind your target as you open fire, unless you are able to consistently fire off single shots from the M60. If boxed in by the Common Infected, whoever is at the front should crouch so that Survivors from behind can fire over their heads.
  • With four unlimited M60s, taking down Tanks will be easier than normal, especially as the M60 (with unlimited ammunition) is the fastest gun at taking down the Tank on all difficulties. Survivors may have to watch out for friendly fire if there is not enough room to maneuver.
  • Witches may prove a little bothersome as nobody will be able to cr0wn the Witch. In this case, Survivors may have to all shoot at her from a distance at the same time and take her down before she reaches the Survivors. Using a Molotov will help in reducing her running speed slightly, as well as giving the Survivors a fiery target to shoot at. For other tactics involving taking down the Witch without using a shotgun, see the section on killing the Witch on her article. Alternatively, if possible, just run past the Witch at the same time or in pairs with flashlights off to avoid fighting her, especially on Expert difficulty.
  • If a Hunter or Jockey gets too close, it may be preferable to shove it to death due to the M60's damage, especially at higher difficulties. If any Survivor Bots are on the team, they can shoot the Special Infected to death without fear of friendly fire.
  • The M60 cannot gib the Riot Infected in The Parish due to its armor. Remember to shove it to expose the back or move your positioning.
  • Laser sights will increase the accuracy of the M60, especially when shooting on the run. Be sure to look out for places where they usually spawn at, and get the entire team to upgrade their M60s.
  • If Survivors are incapacitated, they will have access to a Magnum, which works better than the usual Pistol(s) at taking down Common Infected attacking while Survivors are downed. While the Magnum could be used for doing long distance shots, the M60 can also do long distance shooting by crouching. This makes the Magnum basically only useful when Survivors are incapacitated, or when attempting to do single shots at long range if the user is unable to gently squeeze off single shots from the M60.
  • Throwable weapons such as the Molotov, bile bomb and pipe bomb still spawn.
  • For all intents and purposes, the Mutation plays exactly like the default Campaign with no changes to the Infected.

Iron Man[]

  • In this Mutation, it will play almost the same as Realism and as such, many of the tips for playing Realism will apply to this Mutation.
  • With the lack of ammo piles, however, this will mean conservation of your existing ammo. Use your secondary weapon, be it a Pistol or melee weapon often. Don't get too attached to your gun, especially if it has a laser sight on it. Be prepared to swap it as soon as you come across new guns.
  • The Magnum works well against the Common Infected due to its one-hit-kill properties carrying over to Realism.
  • The need to stick together and survive is even greater in this Mutation due to the Realism rules and the main rule of Iron Man Mutation, which is if the whole team is incapacitated or all the human players die, the team will be booted to the lobby.


  • In this Mutation, Infected players will spawn as Tanks only. There are no other Special Infected to worry about. However, having to deal with four Tanks is extremely troublesome.
  • Common and Uncommon Infected still exist. They can and often will slow you down, so try to eliminate them before they swarm you. For these purposes, players should be equipped with shotguns and melee weapons.
  • First aid kits have been removed, with all spawn points for them being replaced by pain pills.
  • Simply put, due to the nature of one Tank being bad enough, let alone four, a solid tactic is to group together and keep running. Keep moving towards the safe room. DO NOT deviate from the main path under any circumstance, as it will allow the Tanks to catch up to you.
  • If a teammate is incapacitated, in most circumstances during this Mutation, they will have to be abandoned, as the time reviving them can be more than enough for a Tank to catch up to you. If all the Tanks are dead or very far behind, it is possible to revive and incapacitated player. Make sure you use an Adrenaline Shot if you have one to shorten the time needed.
  • During Crescendo events and finales, keep moving, and never stay in one spot. Keep moving so the Tanks cannot gain the advantage.
  • Tanks during this Mutation have 3000 health, compared to their normal Versus health of 6000. If forced to take on a Tank, concentrate fire on one to bring it down faster.
  • A Molotov will be extremely useful to panic the Tank players if it can be used at blockage points to either prevent the Tanks from running through, or forcing them to run through so they catch on fire. Gas cans serve a similar function with a longer lasting fire, except they need to be shot first.
  • Bile bombs may also be handy if found to slow down the Tanks with Common Infected, as well as blurring their sight for a limited time.
  • In The Bridge, Tanks will spawn in the safe room before the bridge has fully lowered, leaving all Survivors open to attack with nowhere to run. Setting the safe room floor on fire with a Molotov will at least help slow them down if the Survivors can survive the initial onslaught, as they will all eventually die from the flame and wait for respawning.
  • The Passing and Dead Center finales are the hardest to complete, as the Tanks will be waiting for the team when they disembark, often resulting in human team getting incapacitated before they can complete their objective. Should the human players manage to escape, they will also have to grab gas cans to complete the objective, leaving them defenseless against the horde and Tanks.

Hunting Party[]

  • In this mutation, the main attacking Special Infected are Hunters. Being able to deadstop or kill them from afar will be key to survival. You will still have Tanks, Witches and Common Infected in this mutation.
  • There is a short delay after leaving the safe room before the Hunters start spawning (much like the Tanks in the Tank!!!!! mutation), so try to cover as much ground as possible.
  • Hunters tend to spawn together in groups of four. As they are all pinning infected, it may be possible for the entire team to be overwhelmed by sheer numbers. Stay close to each other and immediately rescue each other if someone is pinned.
  • Be alert! Hunters begin crouching the moment they come into close proximity with Survivors, causing them to growl as a warning. In addition, keep an eye (and ear) out for Hunters during horde attacks.
  • Up to 6 Hunters can be present in this mode.

Lone Gunman[]

  • In this Mutation, the player is only armed with a Magnum, which can take down Common Infected and Boomers in one shot. However, attacks of the Common Infected have a 15x multiplier.
    • On Easy, it takes 7 hits from the front (14 from the back) to incapacitate the player.
    • On Normal, it takes 4 hits from the front (7 from the back) to incapacitate the player.
    • On Advanced, it takes 2 hits from the front (3 from the back) to incapacitate the player.
    • On Expert, a single hit to the front or back instantly incapacitates the player.
  • Move fast, and try not to use the flashlight if possible, as it will alert Common Infected faster within their proximity. Try to avoid killing as much Common Infected as possible, as it will prevent as much Common Infected from appearing in front of you.
  • In some cases, it will be better to run and gun, and others just sit in a corner and shoot. Do the former if there are not many Infected in the area, but be careful, but do the latter if vomited on or in a Crescendo Event without environmental advantages (such as the fire in The Hotel) or throwable items.
  • Try to also make as much use as possible of throwable grenades (preferably in Crescendo Events).
  • Try to take as many shortcuts as possible.
  • Close every door in the surroundings to buy time, as the Infected must break through to reach you.
  • If a horde approaches, make use of surroundings if possible to funnel the Infected from less open spots, such as a closet or room or doorway.
  • Note that Tanks and Witches can still spawn. Like the Boomer, these Special Infected are not affected by the damage multiplier that is active in this Mutation, they are just as powerful as they are on a standard Campaign.
    • As the Magnum is not powerful enough to kill the Tank quickly, a Molotov is absolutely essential in killing him.
    • The Witch is too powerful to kill with a Magnum alone (unless environmental factors disrupt her movement). Never attack a Witch unless she is blocking the path.

Healing Gnome[]

  • No First Aid Kits, Pain Pills, or Adrenaline Shots will spawn and similar to Bleed Out, your health is temporary and will always be draining. Keep moving and don't linger so that the team will have a better chance of surviving. Defibrillators will still spawn, but not as frequent.
  • You can only heal by holding the gnome. Always let someone with the lowest amount of health hold it until they are back at full running speed again. Anyone who is holding the gnome will regain 1 health point every half second.
  • While someone is holding the gnome to heal, they cannot use any weapons other than shoving Infected back. Protect the person who is holding the gnome and drop the gnome if a Tank or a horde comes so that everyone can handle the threat.
  • In the beginning of the first chapter in any campaign, your health will not start to drain until you leave the safe area.
  • Since the mutation follows Last Gnome on Earth rules, you cannot continue to the next area unless someone is holding the gnome when they reach the safe room. If the gnome gets tossed to a place where the survivors cannot retrieve it, the game is unwinnable and you will have to restart.
  • When the survivors advance to the next level, their health will be fully restored.
  • It is highly recommended that this mutation is played with a full group of friends. Bots cannot hold the gnome and refuse to carry it, so they will eventually be limping too slowly to stay with you and will constantly be slowed down by hordes.
  • Be careful with explosions if the gnome is not being held (such as explosions from pipe bombs or a Boomer). The explosion will send the gnome flying and possibly to an unreachable location.
  • Similar to Last Gnome on Earth, you can obtain a second gnome in Dark Carnival by winning the shooting gallery game at The Fairgrounds. The second also has the ability to heal when being held, so two people can hold both gnomes to heal at the same time. However, this will also leave only two gunners, so heal wisely.

Flu Season[]

  • In this Mutation, no Special Infected apart from Boomers, Spitters, Tanks and Witches will spawn. As Tanks and Witches appear erratically, they only appear in scripted areas. This means that Tanks will only appear in finales (apart from the single Tank in The Sacrifice) and no Witches will appear (apart from the "Bride" Witch in The Riverbank).
  • Idle Common/Uncommon Infected do not make an appearance in this Mutation; they will only appear during panic and crescendo events.
  • Spitters and Boomers have been greatly enhanced for this Mutation. Up to six (three of each) of these Special Infected can spawn, without any delay, meaning that once you leave the safe room area, they'll spawn immediately. Boomers have no cooldown on their puke and move incredibly fast; roughly on par with a startled Witch. Spitters have a greatly decreased cooldown time on their spit.
  • The most optimal method for this Mutation is two have two players use shotguns, and the other two to use assault or sniper rifles. The rifles will take out the Boomers from a distance, while the shotguns will clear out any nearby Infected if someone gets biled. Melee weapons also clear out hordes at an efficient rate.
  • Items seem to appear less frequently in this Mutation. For obvious reasons, Bile bombs do not make any presence in this Mutation, as it would be canceled out due to the increased presence of Boomers.
  • Because of the increased rate of Boomers and Spitters, advancing through a level is often slow as Boomers slow down the team with hordes. Depending on the location you are at, you may want to turtle until the coast is clear, or press forward.

Encores and Developer's Choice[]

In 2010, after every four or five weeks, Valve would announce an encore week in which the community vote for a Mutation to be replayed. Only recent Mutations that have been played may be voted for. Alternatively, the developers would choose to replay one of their chosen Mutations for a week as a "Developer's Choice". The following encore weeks re-showcased the following Mutations:

  • Friday, May 21st (week 5) had Last Gnome on Earth return for another week.
  • Friday, June 25th (week 10) had Chainsaw Massacre reappear. On the Xbox 360, it led with 43% of the votes. However it was much more close on the PC. Chainsaw Massacre won by 1%, specifically 500 more votes, than the second most voted PC Mutation: Headshot!.
  • Friday, July 30th (week 15) had a split vote. For the PC, Versus Survival won by 6% more than Four Swordsmen. However, on the Xbox 360, Four Swordsmen won by 10% more than Versus Survival.
  • Friday, August 20th (week 18) had developers choosing Last Man On Earth to be replayed for one week on both PC and Xbox 360.
  • Friday, August 27th (week 19) had a split vote. For the PC, Gib Fest won by 5% more than Versus Survival. However, on the Xbox 360, Chainsaw Massacre won by 5% more than Gib Fest.
  • Friday, September 3rd (week 20) had developers choosing Hard Eight to be replayed for one week on both PC and Xbox 360.
  • Friday, September 10th (week 21) had developers choosing Follow The Liter to be replayed for one week on both PC and Xbox 360.
  • Friday, September 17th (week 22) had developers choosing Healthpackalypse! to be replayed for one week on both PC and Xbox 360.
  • Friday, September 24th (week 23) had developers choosing Versus Survival to be replayed for two weeks on both PC and Xbox 360, as the team will be busy 'working on their infrastructure'.
  • Friday, November 12th had Taaannnkk! reappear out of the five new Mutations, leading with an overwhelming majority vote of 51% on Xbox 360 (second highest vote was Hunting Party with 17%), and 47% on PC (second highest was Healing Gnome with 17%).

Achievements & Awards[]

Unlock the Gnome by playing any 6 Mutations.

Play 6 Mutations.


  • Week 2 of the In-Game blog made a poll, asking if Realism Versus should have a permanent slot in the game modes. Due to majority votes, Realism Versus is now a permanent game mode.
  • The Mutation Bleed Out was previously bugged, as on The Passing, the original Survivors would sometimes throw first aid kits down to the new Survivors during the finale The Port. Although this was quickly patched by Valve in the 30th April update, the bug is still currently active on the Xbox 360 version of Left 4 Dead 2.
    • Furthermore, if in a black and white state after being incapacitated, taking pain pills will return color, but the heartbeat (signifying emergency state on Third Strike) can still be heard.
  • The Mutation Last Gnome on Earth may be slightly buggy. When you play Dark Carnival, on the second chapter, you can obtain a second Gnome Chompski from the shooting gallery and progress through the whole campaign with two gnomes, who are treated the same as each other (Common and Uncommon Infected will equally go after the gnome carriers), yet when on your last "life" i.e. seeing in monochrome, only one of these will be outlined. This has yet to be patched, if it is a bug.
    • Getting any gnome into the rescue vehicle counts for the Guardin' Gnome achievement if not obtained already. You can even start the game at The Concert, then play through to get this achievement.
    • When you are playing Dead Center on the the first chapter, make sure you hold the gnome in the elevator, if not he will fall right through the floor and become unreachable.
    • This can also happen on the ferry on Swamp Fever, as the gnome falls through the wood and lands in the insta-kill water.
  • In the Mutation Last Man on Earth, the guns in Whitaker's Gunshop are different. Where the Pump Shotguns and Submachine Guns usually are, their Tier 2 replacements will occupy their space instead.
    • In the Atrium after you have finished pouring the gas cans and escaped, the Common Infected appear outside.
    • It is possible to play The Sacrifice in Last Man on Earth. However, this makes the finale rather illogical, because at the end you still sacrifice yourself, which doesn't save anyone.
    • Many of the cutscenes are messed up because the other Survivors are not there to act or speak their lines.
    • You are not exactly the "Last Man on Earth", since the rescuers are still heard talking through the radios in some campaigns. The drivers of the rescue vehicles still can be seen.
  • In the Mutation Chainsaw Massacre, on The Passing's finale the original Survivors will be using Pistols instead of their normal Tier 2 weapons. Louis, however, continues to use the Heavy Machine Gun.
    • This mode is currently bugged. Similar to the Bleed Out Mutation bug during The Passing on the finale (see above note), the original Survivors may occasionally throw down Tier 2 weapons (including the M60) to the new Survivors during the finale The Port, letting Survivors fight with a Chainsaw and firearm.
    • During this Mutation it is possible to find other primary weapons in the campaign — for example in Hard Rain's second stage Sugar Mill, at the safe room where the diesel gas cans are, there is a single Pump Shotgun on the ground. As the gun is loaded to its maximum capacity, it can serve as a backup weapon for dealing with Boomers and Spitters. As the Mutation is meant to be revolved around using the Chainsaw or Pistols you begin with (since no firearms or ammo piles spawn generally), this is a bug.
    • Laser sights will still spawn in this mode, but they are unusable since you have no primary weapons. The only exceptions are when you obtain a primary weapon via the bugs described above.
  • In the Mutation Room for One, playing the whole finale will get you the campaign achievement if you don't have it. Even if you're not the one to make it into the rescue vehicle, you will still get the achievement as long as you are alive when the campaign ends. For example, making it into the Dark Carnival helicopter, and getting MIDNIGHT RIDER.
    • In the Hard Rain finale, Town Escape, if a Survivor jumps from the flat level dock and not the inclined ramp onto the boat, that Survivor will live but NOT be counted as the winner. The Survivor that jumps from the inclined ramp is the winner even though the ending animation might show otherwise. This may be a bug.
  • In the Mutation Headshot!, it is possible to decapitate a Common Infected and they will still be standing. This is shown much more often if you headshot them.
    • When incapacitated, shooting Common Infected anywhere translates into an instant headshot, so fending yourself when incapacitated is actually easier.
    • When a Common Infected is killed with a Frying Pan or Nightstick, it doesn't lose its head.
    • Riot Infected are extremely hard to kill in this Mutation as they have to be shot/decapitated from the back of the head.
    • The update for the Mutation Headshot! has not been obtainable by a lot of Xbox 360 owners of the game (if not hooked up by LAN connection to their modem). After they start up the game and get to the main menu, the Blog Post from week 1 of Mutations will be shown there, and Realism Versus will not have its usual permanent slot, but it will be available under the Mutation slot. Reasons for this are so far unknown, though it's most likely due to a bug or the connection to the servers. Additionally, the date of the Blog Post will say March 23rd, 2010, despite that the original date of The Passing's official released date was on April 22nd, 2010.
  • In the Mutation Four Swordsmen, unlike Chainsaw Massacre, Survivors immediately start the campaign with Katanas in hand. However, the cutscene played at the start of each campaign was designed for the Survivors to have the Pistol in their hands, so there may be some slight animation errors in how they hold the Katana with their pistol grips. This is immediately fixed as soon as players control the Survivors, as they will hold the Katana normally afterwards. Also, if killed and revived from a closet, you will start with a pistol, likewise if a Survivor dies and re-appears in the safe room.
    • The Mutation Four Swordsmen appears as that name in the Mutation in-game option, but on the update and Blog Post (in-game as well as website blog), the Mutation is known by the longer name Four Swordsmen of the Apocalypse. It is unknown why Valve chose to use longer and shorter variations of the Mutation's name rather than sticking with one single name.
    • On Swamp Fever, at The Swamp, just after the hanging military man in the trees, a Magnum and a Katana can be found at the small wooden dock. If Survivors wish to break the theme of 'swords only', the Magnum can be handy for dealing with Special Infected at range. As the Katana is meant to be the only weapon for use in this Mutation, this is considered to be a bug.
    • Similar to Chainsaw Massacre, it is possible to find other primary weapons in the campaign — for example in Hard Rain's second stage Sugar Mill, at the safe room where the diesel gas cans are, there is a single Pump Shotgun on the ground. As the gun is loaded to its maximum capacity, it can serve as a backup weapon for dealing with Special Infected from a distance, or for killing Witches by cr0wning them. As this Mutation is meant to be revolved around using only the Katana, this is a bug.
    • Laser sights will still spawn in this mode, but they are unusable since you have no primary weapons. The only exceptions are when you obtain a primary weapon via the bugs described above.
  • In the Mutation Gib Fest, during The Passing, the original Survivors are still capable of dropping laser-sighted M60s. Though the M60 drop itself is pointless, it's still useful for its laser sight (given that the Survivors have not obtained laser sights beforehand).
    • Also, in some campaigns (though rarely) like the Left 4 Dead 2 port of Death Toll or Cold Stream Tier 2 weapons may still spawn. Such as one-Combat Shotguns at the beginning of South Pine Stream or Auto Shotguns during the escape from the Sugar Mill.
    • It is possible, but extremely rare, to find a Grenade Launcher in certain Gib Fest Campaigns. As the Grenade Launcher was ever only coded to have one shot per magazine, this results in the grenade launcher having almost no cooldown between shots (it can fire as soon as the coding for infinite ammo kicks in and replaces its expended shot).
    • The inverse can happen when playing on Cold Stream. The players and bots will spawn with their standard weapons, and may get a choice between a submachine gun variant and a pump shotgun variant, with a few secondary weapons spawning nearby. However survivors will not get access to the M60, even if killed and revived. It is possible that the above glitch may happen and spawn a M60 or a Grenade Launcher in certain areas.
    • Similar to Chainsaw Massacre and Four Swordsmen, it is possible to find other primary weapons — for example in Hard Rain's second stage Sugar Mill, at the safe room where the diesel gas cans are, there is a single Pump Shotgun on the ground. As this gun has unlimited ammunition too, it can serve as a replacement for the M60. As this Mutation is meant to be revolved around using only M60's and Magnums, this is a bug. Bots are automatically pick up the shotgun as their programming forces them to discard the M60, Chainsaw and Grenade Launcher immediately if possible.
  • In the Mutation Iron Man, it is still possible to find, and also use, Defibrillators. Though this Mutation states that once you die, you're dead permanently, and yet there are still Defibrillators that you can find and use, this might be a bug, but is not completely certain, as the Mutation is based on Realism rules, which allow Defibrillators to revive Survivors.
    • The in-game tagline description of the Mutation Iron Man does not mention "no ammo". It just states no respawns, no restarts, all tension, unlike the Blog Post (in-game and web blog) which states no respawns, no restarts, no ammo, all tension.
    • The in-game tagline description of the Mutation Iron Man says that there are no respawns and yet after Survivors make it to the safe room, all dead Survivors are respawned. This may either be for gameplay balance or a bug.
  • The Mutation Versus Survival has also been addressed officially by Valve in the blog as Survival Versus. It is unclear which name has overall precedence, as Valve makes use of both names. The Mutation name as it appears when selecting the game mode, however, is Versus Survival.
  • The Mutation Taaannnkk! has also been addressed officially by Valve in the blog as TAAANNNKK!! (in all capital letters and two exclamation marks), as well as Taaannnkk!! (with two exclamation marks instead of one). It is unclear which name has overall precedence, as Valve makes use of all three names. The Mutation name as it appears when selecting the game mode, however, is Taaannnkk!.
    • Sometimes, Tank players may spawn in an area where it is impossible for them to reach the Survivors due to no climbable walls. This is a bug.
    • Tanks spawn with half the amount of health they would normally get in a Versus game (3000 instead of 6000). This is to balance the number of simultaneous Tanks, giving the Survivors a small chance of survival.
    • Tank spawns can sometimes be unfortunate to the Survivors as it is possible for Tanks to spawn in the same general area (room, hallway, safe room, etc.). It is possible that Tank spawns are based on the line of sight of the survivors. This can be deadly to players who are not familiar with The Apartment of No Mercy as it is possible for Tanks to spawn directly by a Survivor.
    • Unlike Versus mode, this Mutation only spawns Tanks equal to the amount of players on the Infected team.
    • Despite the description saying "Every Special Infected in this Versus game is a Tank!", Witches can still spawn which may be unfortunate for the Survivors if one spawns in their path.
  • In the Mutation Hunting Party, Tanks and Witches will still spawn.
  • In the Mutation Lone Gunman, items such as Laser sights, Defibrillators, ammo upgrades, an extra magnum, and ammo piles will spawn even if they cannot not be used.
    • Despite the tagline saying only the horde and Boomers spawning, Tanks and Witches will still spawn.
    • On The Sacrifice at Port Finale, the final generator still has to be restarted, but due to the nature of the Mutation, nobody needs to be left on the bridge in order to restart the generator to complete the campaign.
    • The picture for Lone Gunman has an Beretta 92, yet there is no Beretta 92 in the game.
  • In Hard Eight mutation, there's a rare chance where Survivor Bots will pick up a melee weapon, unlike normal campaign where they'll only use pistols.
  • In the Mutation Healing Gnome, as the Survivor Bots cannot hold throwable items, they will have no methods of healing.
    • As can be seen in this video, in Swamp Fever's Plank Country, you can shoot a gnome off of the sign allowing you to have two gnomes.
  • In the Mutation Last Man on Earth, despite the mutation only allowing you to be incapacitated once without First Aid, the gamemodes.txt file doesn't have "sv_max_incapacitated_count" set to "1".
  • Some of the Mutation names along with their taglines appear to be based on certain themes, imagery, or others:
    • Chainsaw Massacre is likely a reference to The Texas Chainsaw Massacre franchise.
    • Iron Man is likely derived from the Ironman Triathlon, in terms of how grueling the mode will be (Ironman Triathlons have a mantra where "just finishing is a victory"). A number of other games, such as Halo 3, also have modes based on the name.
    • Four Swordsmen (along with its longer name Four Swordsmen of the Apocalypse), along with its tagline Four Swords against plenty of apocalypse!, is a play on the Four Horsemen of the Apocalypse from the last book of the New Testament of the Bible. It could also be a reference to The Legend of Zelda: Four Swords, though this is unlikely.
    • Last Man on Earth, along with its tagline You will become legend to the infected as the last human left., is a reference to the novel I Am Legend and its related film adaptations, where the protagonist is (what he believes) the last surviving human in a world full of infected beings (in this case, vampires, who he quickly becomes a legendary monster to). The title is derived from the Italian movie The Last Man on Earth (L'ultimo uomo della Terra), which was based on the I Am Legend novel.
      • With the infected beings in the novel and film adaptations being vampires, this might also lead into Francis' mistaken belief that the Infected are vampires due to their similar behavior, aggression, and running speed, in comparison to stereotypical film zombies which move at a lumbering pace.
        • The name of the mutation may also be based on Zoey's cut line from the old versions of the Left 4 Dead intro, where Bill would wipe the puke off on Francis's vest after being asked if she's interested in Francis's "improvement".
    • Bleed Out is a colloquial term for exsanguination, the fatal process of total blood loss. It is more commonly known as "bleeding to death". It is also a reference to a Survivor bleeding out to death if left incapacitated for too long.
    • The Last Samurai may be named after the movie of the same name, where the protagonist is armed with just a sword against superior odds. The protagonist in the movie, however, was only alone in terms of racial group.
    • Flu Season takes the two Special Infected whose special attacks are analogous with the biological illnesses associated with the flu (in this case, vomiting). Along with the timing, "flu season" is commonly associated with winter, which is when the Mutation happened to take place.
  • Some achievements may be easier to earn on some Mutations. Examples include:
  • Although Realism Versus has become a permanent game mode, playing it counts towards the MUTANT OVERLORD achievement, if not already obtained.
  • Even on a Mutation that excludes Common Infected, they can occasionally be seen milling about idly on various stages. Additionally, custom campaigns that force Common Infected spawns will still result in encountering aggressive groups of them in these Mutations.
  • Chainsaw Massacre, Versus Survival, and Gib Fest are currently the most repeated Mutations, having appeared three times altogether as of November 19th 2010. Chainsaw Massacre and Gib Fest have returned via encores, while Versus Survival has returned via Developer's Choice and an encore.
  • The mutation Special Delivery was previously bugged. If a player played the mutation with bot-controlled Srvivors, sometimes the bots may disappear completely. This would remove the in-game character, the health meter at the bottom of the screen and the health meter in the side menu for the remainder of the campaign. Since then Valve has fixed it in the community1.nuc file, preventing this bug from ever happening again.
  • In the Death's Door mutation, completing The Sacrifice alone is impossible since the game restarts as soon as the player restarts the Generator instead of displaying end credits due to the fact that incapacitation is disabled in this mutation.
  • In The Last Stand Update there was a mutation called TrainingToolbox which is for players for to understanding/Practice each weapons and infected and different scenarios for players to understand the game well, But it was "Cut" due to the fact that because it doesn't fit in the rest of the content very well, however you can still get it from the workshop since it was uploaded there instead. (https://steamcommunity.com/sharedfiles/filedetails/?id=2237332273)



Videos Walkthroughs.

Single/Co-op Mutations:

Versus Mutations: