Why not go with the Source engine from Valve? DayZ could be a L4D2 mod. The game al ready has a lot of things you could use like: zombies, health packs, painkillers, weapons and so on.

I just got Arma 2 and OA via Steam. Steam keeps the games up to date by it self. I used DayZUpdater to install the mod and launch the game via steam. My problems: When I brows for servers there are many servers that I can't join. The version of something doesn't match up, it shows this number in the lower right corner. What is this and how can I update this? When I finally find a server that I can join I'm a crow. How do I become a player and why do I start as a crow?

Wrong place to post this, please remove.