Red Orchestra started out as a mod to Unreal Tournament 2003, many years ago. It later got a stand-alone release, now via steam. Quite entertaining in some manners, but quite lacking in how infantry moves. Be prepared to be mowed down by a pixel and some annoying german kid. Tactically, the game has some flaws. I play COD4 with some of my olf friends, but it is mostly a run and gun sort of thing.