Left 4 Dead is a co-operative multiplayer action game from Turtle Rock Studios, the creators of Counter-Strike. The game takes place in an apocalyptic world where a highly virulent strain of rabies has spread quickly through the human population, turning those infected into violent psychopaths. Players are among the few seemingly immune to this virus and must fight their way to safety or die alone alongside other Survivors. Left 4 Dead is built with version 2 of Turtle Rock's advanced A.I technology and runs on Source Engine for enhanced visuals and gameplay experience. In Left 4 Dead, players will have to work together if they want any chance at survival in this chaotic post-apocalyptic world.