Common Infected

Common Infected, also known as The Horde are the most commonly-faced enemy and the easiest to defeat. They are completely AI-controlled and fairly weak. Their strength lies in the fact they attack in groups sometimes as large as several dozen, known as hordes. While they seem capable of ignoring pain, they can still be killed as easily as a normal human can. They are capable of climbing ladders and scaling objects. The default amount of infected that are spawned in a mob is around 30.

Common Infected react violently to the pipe bomb and will ignore Survivors to investigate it instead.



Appearances and Action
Common Infected come in variety of appearances, both male and female. They are the victims of the vicious virus only known as The Infection that is sweeping through the area. Common infected do not differ in appearance from a healthy human as much as special infected do. Some infected models can be seen in any scenario of the game, while others, such as the infected patients in Mercy Hospital or airport custom officers in Dead Air are only encountered at certain areas. When not attacking, they are very vulnerable when sitting down, leaning on walls, or simply standing. They are easily provoked by light, sound, or touch, but are normally only dangerous in large groups or when completely surrounding a player. The heads, arms and legs can all be shot off, this happening easiest using a shotgun or hunting rifle. The Infected react naturally to gunfire in their vicinity, turning towards the sound to attack the shooter. Shooting one in the foot will cause a very different reaction than shooting one in the chest with a pump shotgun. They are often seen engaging in bizarre activities (e.g. vomiting, attacking inanimate objects, fighting each other) when unaware of the Survivors, but begin to rush at you when they spot you. A common infected's attack slows down the target player, meaning that it's hard to run away from a mob of them that is close to you.

The infected appear to lack a sense of self preservation, as they will actively charge into flames, explosions, and against superior forces of the survivors and their weapons, even if they have encountered these things before. A possibility is that the infections has affected their brains to such a degree that they only think of spreading it, and that this is possibly what the infection is attempting to do, which is spread as far as possible. The infected also are not known to feed or drink, and it is possible that the infection has caused them to no longer perform these necessary life functions. This may indicate that the infected may eventually die of starvation or dehydration, and possibly even exposure to the elements as the infected do not seem to seek shelter in conditions that non-infected would.

Tactics
Common Infected are only strong in numbers. Sticking together is key to keeping them off of you and your teammates' backs. If you are concerned about conserving ammunition, consider using the pistol, which kills them in just a few shots or one headshot on any difficulty.

When a horde is about to attack, the best tactic is to back into a corner (preferably) or a wall. Assign the front two Survivors to crouch and melee continuously while the two Survivors behind them stand and fire their weapons at them. This works equally well when slimed by the Boomer.

Pick off lone infected whenever you can. When entering a new area, swap to pistols and take out as many lone infected as you can from the entryway as long as it stays quiet. The Director has a tenancy to spawn hordes once you reach the mid-point of areas, and this "event" will cause any idle infected in the area to attack as well. In versus, however, it is unlikely the boss infected will allow you to sit in one place long enough to clear a room in this manner, so keep moving.

The hunting rifle can kill multiple infected with just one bullet as the power of the rifle can penertrate more than one of the infected. Have one ally with a hunting rifle if a mob is spawned at try to get the infected to run in a straight line behind each other to maximise kills.

Trivia
Once in a great while, a glitch may occur a common infected may become invulnerable to damage, meaning that no matter how many times you shoot or hit it, it will not die. Your AI partners will ignore it, even when it continues to attack them. The only way to "beat" it is to knock it into a room and then close the door, running off while it is still trapped, giving you enough time to escape.

Another glitch is where infected are stood stationary with their arms parralel at 90 degrees, these infected can be killed but ragdoll physics do not take effect. Also these glitched infected can stop survivors from moving and so it has been seen that survivors can be trapped by these glitched infected. To combat this you must restart the server upon which you are playing.

A third glitch can occur when one tosses a pipe bomb, such as throwing one towards a horde, and occasionally some infected may stop moving and glide back and forth, but you are still capable of killing them.