When a player starts a new server, 2000 zombies are spawned in random locations, though typically in cities and towns, in hordes or individually. Once a zombie is killed, it stays dead, meaning that it is possible for the player to clear all zombies from a server. Zombies are aggravated when a player comes within their 20 foot detection radius, provoking them to run and attempt to attack the player.
Zombies are found in areas where civilization would have been before an outbreak of zombies occured, acting as a challenge for the player to gather supplies to aid their survival.
Zombies can take a certain amount of damage, and it is consistent for all zombies. Zombies can be killed with one shot to the head, three to the body, or one whack of the Hatchet. However, at ranges longer than 30 feet, Zombies will revert to a 2-D model, and can be killed by a single shot to anywhere on the body. Zombies will often "spasm" upon death and fall to the ground, continue to move for a few seconds, then lay still. Zombies have a 20-foot detection radius, and will detect players through walls or other obstructions.
Zombies, while they generally stay inside areas of former human civilization they will wander around these areas until a player enters their detection radius. When they detect a player the zombies will give some sort of scream or howl and give chase to the player until they are killed or the player flees far enough away to lose them.
However it should be noted that occasionally zombies will not immediately give chase once they detect a player, instead they will simply give a howl and remain stationary, if the Player approaches before it turns the zombie will glitch and likely do damage to the player. It should also be noted that the zombies can also be stuck in a wall but will eventually free themselves, so it is recommended to kill these zombies once they have spotted you.