Zombies have become an iconic staple of the Call of Duty franchise ever since Treyarch’s World at War title. Whilst Zombies has received many different iterations over the years, with Treyarch and Sledgehammer usually taking turns with the reigns of the core game mode with some key changes, this is the first time that a Modern Warfare title will have zombies as a mode. Call of Duty: Modern Warfare 3 is set to feature Zombies, but when can players jump in and fight the undead hordes?