So I just found out about the game DayZ and I was just wondering what exactly I need to play it. I know that DayZ is a mod to ArmA II but there are a lot of ArmA's on steam, ArmA II, ArmA II: Operation Arrowhead, and ArmA II: Combined Operations. What are the bare requirements I need to play DayZ I don't want any ArmA II expansions if I don't need them. Any help is much appreciated!