Killing Floor is a mod for the Unreal Tournament 2004 video game, first released in 2005 as a demo, and full version, later that year. The mod acquired popularity after appearing in several game magazines. It is a survival horror first-person shooter based game, with Co-op multiplayer action. A retail version of the game was released via Steam on May 14, 2009. ... Killing Floor Game play zombies left dead demon hunter steam online max settings