Zombie Panic! Source

Zombie Panic: Source is a cooperative survival horror Half-Life 2 Modification, the sequel to the popular Half-Life Modification "Zombie Panic". As a member of a party of survivors you find yourself without provisions or any military support. Fending off the undead has never been more difficult, but with a large variety of fire arms, explosives, and unique items, the task is not impossible.

Zombie Panic Home[www.zombiepanic.org]
Zombie Panic Download[halflife2.filefront.com]