What do you need to buy and download to play DayZ

The requirements to install and play the multiplayer open-world survival-horror mod DayZ are:

• ArmA II: Combined Operations (ArmA II and ArmA II: Operation Arrowhead)
  
• DayZ Mod Files
  

Both ArmA II and ArmA II: Operation Arrowhead are two standalone games that can be played individually, however DayZ requires both games. ArmA: Free can be used, but at the cost of lower resolution textures.

The downloadable content "Private Military Company" and "British Armed Forces" are not required to play DayZ, but they do enhance the resolution of some of the textures for the players' skins and some of the weapons, vehicles and backpacks.