Left 4 Dead (L4D) is a new action title from Valve, creators of the Counter-Strike and Half-Life games, and promises to redefine the co-operative genre as those titles did for multiplayer and single player action games.

Set in a modern day survival-horror universe, the co-operative gameplay of L4D casts four "Survivors" in an epic struggle against hordes of swarming zombies and terrifying "Boss Infected" mutants.

Valve’s next generation AI technology, allows for games of 1 to 8 players. Players can play as a Survivor or as one of four types of "Boss Infected," each of whom possess a unique mutant ability such as a 50-foot tongue lasso or a giant belly full of explosive methane gas.

The gameplay takes place across four massive campaigns. The "zombie" population of each mission is choreographed by an "AI Director" that monitors the human players’ actions and creates a unique and dramatic experience for them on the fly.

Set in the immediate aftermath of the highly-anticipated zombie apocalypse, Left 4 Dead features single player, multiplayer and co-operative gameplay modes. Next-generation artificial intelligence tailors the pacing and difficulty ensuring a different experience every time the game is played.

The first L4D DLC - dubbed the L4D Survival Pack -- is due for release this spring and introduces a new multiplayer game mode entitled, Survival, plus two complete campaigns for Versus Mode . A Critic's Choice Edition of the game is also heading to retail stores this spring, and will include access to all the content introduced in the L4D: Survival Pack.

In addition, for PC gamers and aspiring developers, the first Left 4 Dead release for the Source Software Development Kit (Source SDK) will allow the creation of custom Left 4 Dead campaigns that will be discoverable via L4D's matchmaking system. The SDK update is also due for release this spring, and is free of charge to all owners of L4D on the PC.

"Since Half-Life launched in 1998, Valve has made continuous efforts to expand the offering of its products beyond what's included on the day of launch," said Gabe Newell, co-founder and president of Valve. "With Half-Life and Counter-Strike, and more recently Team Fortress 2, we've learned that we're no longer making stand-alone games but creating entertainment services. With Left 4 Dead we're extending that tradition by creating additional gameplay and releasing our internal tools to aspiring developers so they may also create and distribute new Left 4 Dead experiences."

System Requirements:

• OS: Windows Vista, XP or 2000
• CPU: 3.0 GHz P4, Dual Core 2.0 or AMD64X2 (or higher)
• RAM: 1 GB for XP / 2GB for Vista
• Disc drive: DVD-ROM Drive
• Hard drive: At least 7.5 GB of free space
• Video: Direct X 9 compatible video card (Video card must be 256 MB or more and should be a DirectX 9-compatible with support for pixel shader 2.0)
• Sound: Direct X9.0c compatible sound card

Left 4 Dead is currently available on PC and Xbox 360.