Dubbed "The Passing," the first game add-on for the horror game Left 4 Dead 2 brings the original Left 4 Dead (L4D1) Survivors down south for a meeting with the L4D2 cast, while delivering new single-player, multiplayer and co-operative gameplay for the PC and Xbox 360. Set in a small town in rural Georgia (and taking place just after the Dead Center campaign of L4D2,) players assume the role of the New Orleans' survivors as they meet with the original characters from the first game.

In addition to the new co-operative campaign and associated narrative, The Passing includes new arenas for Survival, Versus and Scavenge mode and introduce a new co-operative challenge mode of play. The Passing will also include a new "uncommon common" zombie class, melee weapon, and firearm.