Zombies feature in multiple Call of Duty games, such as "Call of Duty: World at War," "Call of Duty: Black Ops" and "Call of Duty: Black Ops II." The original game-mode that introduced zombies to the franchise was in "Call of Duty: World at War."
In the Call of Duty franchise, zombies differ based on the geographical location of the game's stage, or map. The zombies can be either German, Russian, American or Asian. The point of the game-mode is to allow groups of four to work together to fight back waves of zombies, winning only by surviving and retaliating.