Valve announced today that it is working on an expansion to Left 4 Dead 2. The preliminary release date is pegged to early next year (2010).

The expansion is entitled "The Passing" and in a press release issued today hinted that it will take place "down south" somewhere in rural Georgia where the stars of Left 4 Dead 2 will join with the original Left 4 Dead cast and will pick up where Left 4 Dead 2's plot ends.

Once again the game will be available only on the Xbox 360 and PC. In addition to the highly popular co-op campaign new "arenas" will be added for Survival, Versus, and Scavange modes. In addition a new "uncommon common" zombie class will be introduced along with a new melee weapon and firearm.

"The Passing will become the most important campaign in the Left 4 Dead story, as all the Survivors are being called together in one campaign," said Doug Lombardi, VP of marketing at Valve. "It will also be a huge offering of new gameplay content, with something new for every game mode plus a new uncommon common and weaponry."

Keep checking back with Dane of War for more information on this upcoming release.