I've downloaded the free version of Arma 2 off of the official website and downloaded Dayz Commander, it's saying I need Combat Operations...Which costs $$, I kept searching and found that it is possible to run this game using OA/Free Arma 2....But OA also costs money?...I'm interested in giving this game a try but I'm having issues setting it up, if all I need to do is buy CO to run DayZ I will...But I'm just curious if that can be avoided or not. Thanks.