Zombies mode (originally known as Nazi Zombies in World at War) made its first appearance in Call of Duty: World at War, the gamemode consisted of one map, Natch der Untoten (but with three future DLCs had at total of four maps). The gamemode was a simple wave based survival, in which players would have to kill nazi zombies to progress to the next wave with more and stronger zombies each wave. The gamemode has its own storyline just like the campaign of any Call of Duty title but the zombie story does is not cannon with the campaign storyline of any Call of Duty and vice versa.