DayZ is a multiplayer open world survival horror modification (mod) designed by Dean Hall for the 2009 tactical shooter video game ARMA 2 and its 2010 expansion pack, ARMA 2: Operation Arrowhead. The mod places the player in the fictional post-Soviet state of Chernarus, where an unknown virus has infected most of the population, turning people into violent zombies. As a survivor with limited supplies, the player must scavenge the world for supplies such as food, water, weapons and medicine, while killing or avoiding both zombies and other players, and sometimes non-player characters, in an effort to survive the zombie apocalypse.