Zombie Panic: Source is a co-op oriented Survivor Vs Zombie multi-player survival horror modification for HL2. While our main priority is to make the mod as fun to play as possible, ZP:S 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 ZP:S 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, hmm where do I begin, I like the idea of the gameplay where you are a survivor and have to avoid/kill the Zombie team, but there are some issues in my opinion.
One, some official maps aren't really that good, they work well with the system, but they aren't up to standard as in other mods.
Two, due to the limited supply of weapons, survivors almost cannot win. Also this was increased when the team decided to put a cap on the amount of weapons that spawn. If you have a full server, they all spawn, but if there are few, they don't, causing people to lose interest.
Three, its not a game for map makers to, well, make their maps for due to the weapon spawn problems and they cannot make maps as they want it. The team's vision on what the game should be like prevents map makers to make unique maps.
I would say check this mod out, hey its free, but I wouldn't say its great or anything.