Tactics

Assuming a certain level of basic skill and familiarity with tactical shooters, these tactics should help you and your fellow survivors get through Left 4 Dead... alive! As a start, make sure you know all of the Controls.

Above all else, no matter what team you are on, Infected or Survivors, in the end you will be depending on the people around you to survive as well as to have an overall good experience. This game requires cooperation on all sides, so be kind, treat others nicely (don't go overboard with the trash talk), do not belittle your team mates and be patient with the lesser experienced players. With luck, they will return the favor. If not... you might just find yourself left for dead.

Surviving a horde
Infected run fast, come in large numbers, and are often backed up by bosses. This section describes tactics you can use regardless of what your teammates are doing.

Doors
Always close doors when you find them, then blast a peep-hole through it. You can then safely kill infected through the door. If the hole in the door is big enough, go ahead and use melee through the door. This will knock the infected back, saving the door from immediate destruction, and keep you nice and safe. But also remember this can work both ways as good smoker players will grab survivors through the hole in the door while the rest of the group is looking in the opposite direction thinking that behind them is safe.

Closing doors behind you is also useful while you are moving through a level. The AI Director is notorious for sending Infected to you from the direction you just came, and those surprise Infected can really mess up your Survivors quickly. Shutting doors that you just came through can slow down those sneaky Infected and make a difference between becoming incapacitated or dying, and survival.

Boss infected caveats:
 * A Boomer (if detonated too close) will blow the door away and potentially slime the team of Survivors pitted behind it
 * A Hunter can pounce right through a sufficiently damaged door
 * A Smoker can tongue you through a small hole in the door
 * A Witch or Tank can plow right through a door.

Corners and walls
When the shit hits the fan, the best cover in this game can be found in a corner, or failing that a wall to your back. You can then use a melee to knock back infected and shoot when you have breathing room.

Contrary to popular belief, fire extinguishers do not damage either the Survivors or the Infected but they rarely attract the horde, so watch when shooting inside. These things tend to be very common and could potentially ruin your day as opposed to making it better.

Choke Points
A group of Survivors can survive the Zombie Horde if they use a narrow opening to draw the horde to them. This creates a slower flow of infected, and allows the Survivors to concentrate firepower all in one direction, making their defense more successful. Examples of effective choke points are:


 * A narrow hallway.
 * A secure room with only one entrance.
 * A slim rooftop with only one way to get to defending Survivors.

Effective choke point tactics include two rows of survivors near the choke point entrance, where two survivors are crouching up front - usually with shotguns - while the other two survivors stand up in behind and shoot over the front survivor's heads. Crouching survivors can either shoot or melee, and can cover each other while their partner reloads.

Choke points can be a problem when Survivors forget that a room isn't secure from all locations - this leads to surprise zombies breaking in from another point (like through a wall or a ceiling) and overwhelming the Survivors.

Choke points are harder to find in outdoor environments, but you can always use an entrance of a building while inside to fight Infected while they try take on your group.

Other issues include Special Infected taking advantage of the tactical situation. Fortunately Boomers and Hunters can be quickly dealt with. Smokers require Survivors to be aware of their tactics, and they must prevent their teammates from being pulled away too far, or the choke point tactics fall apart rapidly.

On top of things
Sadly, being on top of a car, subway, etc. is of negligible value as cover in this game due to the climbing abilities of the infected. In fact, you'll often find yourself in a situation where you are being attacked along 360 degrees, which in most cases is fatal. However, gaining the high-ground while making sure your back is covered can buy you a good amount of time, due to the fact that it will take a few seconds for an infected to climb up. Use melee or a well placed round or two to finish off a few of the horde.

Additionally, a group of Survivors all defending a high ground point, again using melee and firepower can really slow down Infected's ability to disrupt a staged defense. Working together is key in high-ground defensive positions.

Boss Infected
See also: The Infected

The Tank
Here are some basic tactics to help you defeat the Tank:


 * Keep your distance from the tank if at all possible. You can't expect to survive a one on one with a Tank unless you have a decent amount of health and are an experinced player but having to go one on one with tanks should rarely happen. Take advantage of your surroundings by climbing up and jumping off of ledges, as the Tank leaves itself open whenever it has to climb.
 * Set the Tank on fire using either a Molotov or a gas can. As of January 23, the damage the Tank received from fire is now reflected in the Tank's health. This will reduce the amount of time you require to engage and defeat the Tank.
 * Explosives such as pipe bombs, propane, or compressed air tanks are great for limited big damage, but not as effective as fire, which always does guaranteed damage over time to the Tank. The propane and compressed air tanks will also cause the Tank to reel back, like Infected after a melee attack.
 * Keep clear of cars, fallen trees, furniture, and dumpsters if the Tank is nearby. The Tank will definitely use big objects in the environment and try to punch these objects towards Survivors, which means an immediate knockdown if said object hits a Survivor. Tanks will try to climb over burning barrels, though, setting them ablaze (usually only applies to AI-controlled tanks, but might work with some similar smart players), so moving to put a barrel between you and him will usually have the same effect as a well placed Molotov. Make sure you run fast, because you do not want to be pounded on by a burning tank.
 * If the Tank is pounding a Survivor into the floor, another Survivor can aggravate the Tank and possible draw its attention from it's target by meleeing it in the back. Shooting a Tank won't have the same effect as tapping it on the shoulder with your rifle butt when it's busy killing your teammate. Be aware that a tank can turn around mid swing and smack you if you're trying to melee him.
 * Try to draw the tank into a crouching only area. It can buy you a few seconds while the tank tries to wiggle its way through the area.  Good examples of crouching-only areas are ventilation grates, and ambulances.
 * The Tank can climb, but it slows down. Take advantage of this as you can climb up and down much faster.
 * In closed quarters, all Survivors should concentrate all of their firepower on the Tank. The Tank will pound on a Survivor or two, but everyone should make it out alive.
 * Another useful tactic is to get to an area immediately inaccessible to the Tank. The rafters of a building away from the area that allows one to climb up to it is effective, because the Tank wants to get to you by the shortest route.
 * Whenever a Tank takes damage, its forward momentum slows down (just like yours slows down when infected punch you). If you can light him on fire, hit him with a minigun, and have the other three pump Shotguns into him, the tank slows to a virtual standstill and is quickly dealt with.
 * Lacking a good situation, have one person focus on avoiding the tank while the other three keep him as slow as possible. Make sure to communicate and let your bait know if he switches targets.
 * Explosions, such as pipebombs, propane and oxygen tanks, and Boomers, can knock the Tank back and give you a good three or four seconds to fill him with bullets. Even better if you can push him off high ground, forcing him to come back up.
 * On Expert difficulty, the Tank is a one shot incap for his punch and his rock throw. Once incapped, he kills survivors in two hits. If you see him going for an incapped survivor, you need to aggravate him before the first hit or the survivor will almost certainly die.

Team tactics
This game hates lone wolves like no other. You need a teammates to cover your six and pull you out of the dung hole. Voice communication is extremely useful and most players will need to use it to ensure survival.It is not a requirement but voice communication will help team mates know what is going on around them while normally offering them a quicker rescue response from special infected and being incapacitated.

Single File
This tactic is best used in a narrow or confined space, the player with the most health stays at the front, the player with the next biggest amount of health stays at the back, and protects the back from any spawning zombies or special infected the players with the least health stay sandwiched in the middle there should be roughly about a space for two survivors between each player so if one get pounced,grabbed the other wont be knocked back so they can come to the survivors aid quicker and if the group get sprayed by a boomer attack normally only two of the group will be covered.

Moving
One of the most important things to do on expert difficulty is to always keep moving forward. On expert, the director will almost constantly send hordes and hordes of Infected at immobile Survivors. The longer you take through a level the more hordes and special infected you will need to face.

One very important exception is during a horde attack. Find a spot to cover your back, crouch and do not move! This helps to reduce team damage. If in the open, you can use a teammate's back, so that you each cover 180 degrees.

Zombie buddies
An effective tactic, especially in tight quarters, is to split your team into a point squad and a rearguard. The squad on point is responsible for eliminating all threats from the front while the rearguard puts the hurt on infected flanking maneuvers. This tactic is especially effective because your zombie buddy is close enough to you that they can knock bosses off of you before they can deal damage to you.

Cornered
Surprisingly, four survivors crammed into one corner (or closet) works very well. Deploy two of them in a crouched position doing melee while two more stand behind them and unload their weapons.

CAUTION: This tactic MUST be abandoned with haste if a Tank is present. You can tell if a Tank is coming because there will be cue music, the screen will shake, and the Tank will make distinctive noises, like the other Special Infected.

Lines of fire (and the not-so-friendly fire)
Important rule of thumb: when in doubt hold your fire and use a melee attack

Consider some real-life situations:
 * An infected slips past you and you give in to the temptation to whip around 180 degrees to gun them down but instead destroy your teammate
 * A teammate is man-handling an infected but you decide to "help" them out, only to miss and reduce the survivor count
 * A boomer slimes you so you shoot blind in a panic, thus killing the two teammates who were trying to cover for you
 * A boomer jumps in front of you before he can attack, you shoot and thus damage yourself from the exploding gas bag and become blind and alert the Horde to your current predicament. (if this does happen don't make the mistake of blind firing, mentioned above)

Also, whenever a survivor is between you and a target rich environment, you should either:
 * Hold fire and ask them to crouch (good players will do this automatically)
 * If they are crouched, inform them you are behind them, then open fire (otherwise they might stand up again when you do not expect it)
 * Aim high. Dangerous weapons like the Pump/Automatic Shotguns have a wider area of effect than other weapons thanks to their lack of pinpoint accuracy. Doing this will save your team from potential (and unnecessary) friendly-fire.
 * Switch to pistol(s). Depending on what your primary weapon is, your pistols can be more accurate thus lowering the risk of friendly fire. Also, the relatively low damage of the pistol means that even if you happen to shoot a teammate, minimal damage will be taken.
 * If you're slimed and your vision is obscured, look for your teammates' names, they're still visible. Shoot or push when you see motion and you don't see them.

Dangerous weapons
The following weapons have relatively large areas of effect and thus cause friendly fire havoc. On any difficulty, it is imperative that you know what you are shooting at and have the sense to not stand in front of teammates who are shooting as there are cases where entire teams have been defeated from taking more damage from friendly fire alone than from hordes of zombies. On expert, minimizing friendly fire is absolutely necessary to survive as taking even a few rounds from any kind of weapon is enough to take out a huge chunk of your health and possibly incapacitate you. In the worst case, if you are seriously injured, taking even a round or two of friendly fire can kill you outright.

Shotguns: do not open fire unless you are in front of your teammates. Generally, do not even try to "help" your teammates by picking off targets that are attacking them. If you must shoot, try to fire at the enemy by having them at the edge of your crosshair so that your shot will just barely hit them. This alone may be just enough to kill the enemy and save your friend. However, it's best to just switch to the pistol, which is far more controllable than the shotgun in terms of spread.

Molotovs: this is the single most dangerous weapon to your teammates in the game as the fire damage is indiscriminate and has the potential to incapacitate and/or kill a teammate in seconds. It is even possible to incapacitate the entire team at the same time if the molotov is thrown poorly. Always warn your teammates before deployment and aim it far from survivors. The same goes for the red gasoline jerrycans scattered throughout the game and are relatively common in the levels. Note that fire damage does not kill immediately, even in the case of the ordinary infected, much less a Tank. Because of this, laying down a wall of flame that begins six inches from your own face can be worse than useless.

Pipe bombs: this weapon is dangerous for a different reason than the Molotov. The blast radius is small enough that it's trivial to avoid but be careful as the explosion can set off propane tanks and gas cans turning that trivial explosion into a seriously damage dealing problem. What is downright impossible is to avoid the horde of zombies a badly thrown pipe bomb will attract without destroying. Imagine the following scenario: the survivor team is facing a standing army of infected in front of them and suddenly a horde flanks them from the rear. The player named "Genius" throws a pipe-bomb at the infected hitting the flank. This attracts both groups of infected, detonates to kill the flanking group, and leaves the survivors in the midst of an angry mob of infected that were formerly peaceful in the front. Not good. If needed throw the pipe bomb a medium-far distance away, so if you don't eliminate all of the infected wanted atleast they're far enough away to attack with your pistols or ready for another wave

Compressed gas cylinders: these come in two varieties, propane tanks (white, fat and stubby, relatively common) and oxygen tanks (green, long and slender, rare). Both of these can be thrown and detonated by gunfire to deal massive damage over a wide radius. That's the problem, in fact -- it's sometimes difficult to throw them far enough to avoid blasting yourself or your teammates. It is even possible to detonate these items while they are being held by teammates should a stray round connect with them, dealing grievous damage to the holder in the process. Bear in mind that depending on what you shoot the gas cylinder with, it may not explode immediately. It will usually lose some gas before exploding unless shot with a shotgun or hunting rifle. Additionally, it should also be noted that these objects are highly vulnerable to all sorts of fire damage as well, and will prematurely detonate on their own if they are placed too close to any open flames. Despite the risks associated with these gas cylinders, they are still very useful for set-piece defense situations such as final stands or holding out against incoming hordes.

Dropping down the rabbit hole
This is a source of much agony since infected are often waiting for you at the bottom. You should inform teammates before you jump down and if you are already down there, be aware that teammates will "unexpectedly" drop down from above to intercept your fire.

Teammates left behind
Should someone fall behind and get attacked by a Hunter or Smoker after everyone else has dropped down the rabbit hole, there is still a way to save them. Most walls, ceilings, and floors allow you to shoot through them. The damage you do will be greatly reduced, but you can still end up saving your stranded ally before they are incapacitated.

Cheap But Effective
You're near the final safe-room, low on health, and one of the survivors gets puked on. What do you do? If you want to finish the chapter, you will run. Running from a puked on survior may not be the friendliest tactic, but it can make it possible to finish a long and difficult chapter.

Medical attention
Should you help fallen comrades get up (and cover the rescuer)?
 * Yes! Remember this game absolutely loves destroying lone wolves and every time your survivor count drops you are entering a new world of hurt. When in doubt, just remember: when you're facing endless numbers of infected, having three live people covering your back instead of two live players and one dead teammate can make all the difference in holding off the many waves of undead zombies.

When should you help a fallen comrade up?
 * As soon as they fall and the area is clear. It is impossible to help someone up while infected are attacking you or your fallen comrade. If there's a tank and he is far away, go ahead and rescue.

Once you sustain damage how can you regain your health?
 * 1) Health kit: stabilizes your health and puts you into the green (80 or better hitpoints)
 * 2) Pain pills: temporary health boost, nothing more, but this makes a big difference by letting you run instead of limp and survive potential knock-out blows
 * 3) Dying then getting "rescued", you get 50 hitpoints on rescue(you are either assigned a pump shotgun or submachine gun based on what tier 2 weapon you may have been holding as well with one pistol and nothing else)

What are the mechanics of getting helped back up?
 * Restores you to 30 hitpoints that decrease down to 1 hitpoint over time
 * Only works up to 2 times unless you use a medkit (resets count). You die on the third time. Its easy to tell because your screen goes black and white and your heartbeat gets loud. Make sure to tell teammates, as it is less obvious for them.

If you die, how do you come back?
 * Your teammates will need to advance a certain distance beyond your body into the level
 * You will need to wait 1 minute
 * Your teammates then need to open the closet you will spawn in to complete the "rescue" of a "new" survivor. Its always best to close said closet after rescue, as on some levels the same closet covers a wider than average length of the game.