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.
Zombie Panic: Source v1.5 will introduce the ZPS Barricade System. Here is a short preview of it in action. (Note: The HUD display is not visible in the video but is in fact working in game)