What is DayZ standalone?

DayZ is a multiplayer open-world survival-horror video game in development by Bohemia Interactive - the developers of the ArmA series - and is the standalone version of the mod of the same name.

The game takes place in the ficitional post-Soviet state of Chernarus where an unknown virus has turned most of the population into violent zombies.

DayZ was released as an alpha on 16th December 2013.