Zombie Panic! Source is a cooperative, survival-horror Half-life 2's first-person-shooter modification! While our main priority is to make the mod as fun to play as possible, ZPS plans to greatly expand on the core features of "Zombie Panic!" for HL1, with the obvious new features, impressive visuals, and of course atmospheric maps. More importantly ZPS will not force players to fend against dumb and predictable AI, but instead keep the same intense thrill of surviving against intelligent and persistent player controlled zombies as the original.
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)