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.

RUN44 says

10/10 - Agree Disagree

Simply a great game. If it wasn't free, I would pay for it.