Im joined bye pause lets have some fun! :D http://www.youtube.com/user/PauseUnpause
You nead to buy ARMA 2 or get ARMA 2 Free and also ARMA 2 operation arrowhead to play the DayZ mod. But the DayZ mod is 100% free! ^^
DayZ http://dayzmod.com/ to download links to it or just watch the install tutorial linked below
How to install Dayz mod and arma 2 patch to play the dayz mod (Remember to start arma 2 and arma 2 OA befor installing any mods!) http://www.youtube.com/watch?v=9DkSqgdrJQw