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Left 4 Dead (abbreviated as L4D) is a cooperative multiplayer / horror FPS game developed by Valve Corporation. The game is built using the Source engine and is available on PC and Xbox 360. During early development, working title was "Terror Strike."
The game puts the four men who survived an apocalyptic pandemic against zombies or infected. Infected controlled by the bot, while the player can control up to four Special Infected with special abilities in Versus game mode. The goal of Left 4 Dead for the Survivor is to help each other achieve the Safe Room or Safe Room. The Infected have to work together to stop them.

Left 4 Dead was released on 18 November 2008 in the United States and November 21 in Europe. The game was first revealed in the Christmas 2006 publication of PC Gamer UK with a six-page article describing the playthrough at Valve headquarters. A teaser was released with The Orange Box. The game was first played in the 2007 Showdown LAN in San Jose and at QuakeCon 2007. A demo, originally to be released on 6 November 2008 postponed until 11 November 2008.
In July 2009, Left 4 Dead has 89 out of 100 from Metacritic.
Edition-200 magazine Game Informer ranking Left 4 Dead as # 82 in the top 200 games of all time, this is what they say: "Zombies have appeared in video games in various forms, but no one ever nailed a full-on zombie apocalypse until Valve's Left 4 Dead. intensity of the four-player online cooperative experience utilized in the dynamic by the "AI Director" to set the Infected attack according to the player's performance. With the addition of the memorable characters, interesting story plot, and an online versus mode.
Basic gameplay never changes from map to map, so players will learn their way around pretty quickly. Director makes everything to not monotonous, however, by throwing in a variety of challenges in every level. No two playthroughs are exactly alike.

en.wikipedia.org/wiki/Left_4_Dead