Zombie Panic! Source is a standalone cooperative, survival-horror, first-person-shooter! Set in the middle of a zombie apocalypse, players start as a small group of survivors attempting to stay alive. Each map will have its own objectives to complete and win the round or survive by a period of time.
definitely worth playing. Well thought out, plays very very well. Not much to complain about. You can hourde ammo, weapons, supplies. You can build forts by moving objects and nailing wood boards, very big part of game, really fun.
Highly recommended for especially for hardcore zombie fans.