Just to add to this, that the entire Bohemia Collection (ArmA games etc) are on special this weekend on Steam. Highlights below.

ArmA 1: Cold War Assault - FREE FOR LIMITED TIME - SIMPLY ADD TO YOUR ACCOUNT THIS WEEKEND AND YOU KEEP IT FOREVER.
ArmA 2 - $2.59
ArmA 2: Operation Arrowhead - $3.99
ArmA 3 - $35.99
DayZ: Alpha - $25.49