Killing Floor Full-ISO.

Killing Floor is a cooperative survival shooter that pits you and up to five other players against wave after wave of genetically modified, humanoid "specimens" that have escaped the laboratory and are rapidly overrunning England. Although they are technically not undead, and the game consistently calls them "specimens," these creatures, which travel around in hoards trying to eat people, certainly won't be offended if you mistake them for zombies. These all-but-zombies come in a variety of breeds, you can kill them with a variety of weapons, and that pretty much sums up the game. Killing Floor is satisfying in its simplicity, though the lackluster graphics are a testament to its humble beginnings as an Unreal Tournament 2004 mod. Even as a full game, it forgoes accoutrements such as story, characters, and competitive multiplayer mode, yet where zombie-killing fun is concerned, it delivers in spades.
System requirements
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Operating System : Vista / XP
Processor : 2.4 GHZ or equivalent
Video Card : 128 MB
Ram : 512 MB