The Passing

"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."

- Doug Lombardi The Passing is an upcoming DLC for Left 4 Dead 2 which includes a new campaign and "a new co-operative challenge mode of play." Including new weapons, one melee and one firearm, it also introduces new Uncommon Infected. The Passing will take place between Dead Center and Dark Carnival, in a rural town in Georgia. It will also feature a meet-up between the Left 4 Dead 2 Survivors and the original Survivors. The campaign will be playable in all the game modes, including the soon-to-be released one. Valve hasn't announced pricing details yet, but they do have a target release window of "early spring" for both the PC and Xbox 360 versions.

A programmer at Valve has stated that 16 player Versus will not be a reality, though he did hint at 8 player co-op as a possibility.