left4deadThere were rumors around the web about an upcoming release of some L4D extra content, but now it’s official, as Valve’s Gabe Newell confirmed the release of the Left 4 Dead Survival Pack for PC and Xbox 360. The DLC is scheduled to be released sometime during this spring.

This new release will include a new Survival mode and two brand new campaigns for the versus mode. Also, the PC users will receive this Spring an extra treat: a free-to-download Software Development Kit, allowing modders to prove their skills and create extra campaigns which will be fully supported by Valve and will even feature L4D’s matchmaking system. Also, those who don’t have the game already will be able to buy the Left 4 Dead Critic’s Choice Edition which will be released at the same time with the DLC and development kit.

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,” said Valve’s boss Gabe Newell. “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.”

No pricing, nor an exact release date were announced.