Call of Duty: Black Ops (Nazi Zombies)
Call of Duty: Black Ops may be the best version of Nazi Zombies mode. It added varied maps to the mix, and dropped in random items to keep things fresh. Later versions have more additional stuff, but it almost gets too complicated. Black Ops keeps it simple, stupid. You and up to three friends are trying to hold out as long as you can against hordes of undead Nazis. You're going to go down eventually, but you can choose how long it takes. That's all you can ask for, right?