Left 4 Dead 2: The Passing

Left 4 Dead 2 is a cooperative first-person shooter video game, the sequel to Valve Corporation's Left 4 Dead. The Game builds upon cooperatively focused gameplay and Valve's proprietary Source engine, the same game engine used in the original Left 4 Dead. Set during the aftermath of an apocalyptic pandemic, Left 4 Dead 2 focuses on four new Survivors, fighting against hordes of the Infected, who develop severe psychosis and exhibit zombie-like tendencies. The Survivors must fight their way through five campaigns, interspersed with safe houses that act as checkpoints, with the goal of escape at each campaign's finale.

Left 4 Dead: Survivors is an Japan exclusive arcade game released on April 30, 2014.

This DLC is a custom campaign developed by Matthew Lourdelet, the developer of 2 Evil Eyes and eventually made official by Valve. This DLC features the rest of the original campaigns from Left 4 Dead, Death Toll, Dead Air, Blood Harvest, as well as the later addition of Crash Course. They were ported over to Left 4 Dead 2 in a similar fashion with No Mercy when The Sacrifice was released, featuring the Left 4 Dead Survivors.

This DLC is a port from Left 4 Dead, adding the campaigns The Sacrifice and No Mercy. Initially, it was to be released for the first game alone, but since players would have to own Left 4 Dead to experience the events that explain The Passing, the developers opted to release it for both games. No Mercy was brought over as well because it was the most popular campaign. Both campaigns are available in every game mode. Players will still control the original Survivors, but will find items and Special Infected from Left 4 Dead 2. Five achievements were added, as in Left 4 Dead.