How is Nazi zombies unlocked?

Answer 1

First off, you can only get nazi Zombies on x-box 360. And, if you have a x-box 360 then read this, the only way to unlock nazi zombies is to complete every campaign. (On solo, no multi-player,) it doesn't matter what diffuculty, you just have to beat every campaign without a partner.

Answer 2

Nazi zombies verruckt can only be unlocked by purchasing the map pack1 game add on from xbox live marketplace or ps3 store

cost 800 Microsoft points on xbox

I don't know how much it costs on ps3 I think it costs about £6-£8

hope this helped :)