Tactics

= Tactics for surviving expert mode =

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

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.

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 crapola 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 DO 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.

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.

Boss Infected
See The Infected

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 so useful it ought to be a minimum requirement.

Moving
One of the most important things to do on expert is to always stay moving. On expert, the director will almost constantly send hordes and hordes of infected at immobile survivors. No matter what is going on, always keep moving forward.

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 (Listen for the cue music)

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

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 a regular basis. 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, deliberately "miss" the target to place your shot as far away from your teammate as possible or 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 throw it as far as possible. 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. 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.

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
Your 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.

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

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.

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