Proyect-Z is a zombie survival modification for the Orange Box engine that takes realistic zombie shooter games to a whole new level. And lately, the community for this mod is dieing out, and I'm calling out to all those zombie lovers in the group. This mod is, supposedly, an MORPG, using a leveling system for aspects like speed and accuracy. The game uses Counter Strike Source weapons, but I have just found that all you need is a game that uses the OB engine. If you want more information, please visit this website:
www.moddb.com/mods/proyect-z
Videos of this game are available on youtube, too, if you want to see actual footage of this mod.
Lately, me, and a very few amount of gamers, have been the only ones playing this beautiful mod. So, there you have it, get the mod.