One of the earliest secrets uncovered in Call Of Duty: Advanced Warfare is the existence of a zombie character you can play as in multiplayer.
So how do you unlock the zombie character for Advanced Warfare?
You need to play on the Riot map in Ex0-Survival first. You either join a friend who has already unlocked the Riot map or you unlock it yourself, which means working your way through Tier 1 to Tier 3 maps, with Riot a Tier 4 map. This involves a lot of grinding – you have to complete 100 rounds or more of Tier 3 to unlock Riot – which is why it’s much quicker and easier if you have a friend who has already unlocked the map.
On Riot, you’ll face zombies on round 11, followed by a cutscene and all the zombie unlocks you need to put your undead character together.