Zombies are dead humans that came back from the dead. These Zombies have a complicated history with the Aliens, in the 4th level of Alien Campagin (Epidemic) the Humans, Zombies and Aliens are against each other. But in the 6th level of the Alien Campagin (Breaking Point) the Zombies work with the Aliens.
Levels that Appear
In Survivor Lookout, you start out only with you and J.Rockit. After 20 seconds the first Zombie appears, then 10 seconds later, more and more appear. It is a Deadly Death Match to the end, 2 vs 10 zombies in the Judgement Arena.
Sweep and Clear
Same Outnumbered scores, except that you are equiped with Flamethrower and don't worry about commiting suicide, because you are equipped with Armor Plating. (Immune to Fire and Head, Butt and Crotch shots)
In Disposal there is only one Zombie and three Aliens. So not much to work with.
This is a clash between the three races, Aliens, Zombies and Humans. The Arena is Judgement, and the zombies have 9 lives.
The Zombies are on the Aliens side, and are trying to track down the artifact. They have found it in the Facilty, its a Elimination with 4 on 4, each get 36 lives.
The Zombies have all the basic weapons, except the Vamp Charger. Be careful, it suicides a lot so stay away from it. I recommend Long range weapons and weapons with lots of Power, for the Zombies have Combat Armor.