Arma 2 Arma 2 Operation Arrowhead As I understand it Bohemia hasn t released any sales numbers for Arma 2 and it s standalone expansion Operation Arrowhead but considering that on the official site of the DayZ mod there are over 1 3 Million unique legal users both Arma 2 and Arma 2 OA have sold at least 1 3 M copies each obviously they sold more but that s the only metric available so I suppose both of them can be added to the list either by listing each at 1 3 M or just like Guild Wars putting both together at 2 6 Millions Thanks