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.

Four survivors, Coach, Ellis, Nick, and Rochelle, find themselves abandoned on a hotel rooftop in Savannah, Georgia after rescue helicopters leave without them. In the aftermath of a pandemic known as the "Green Flu" that has turned the population into aggressive zombie-like creatures, the group must fight their way south toward New Orleans, rumored to be the last standing city in America. Their journey takes them through a shopping mall, an abandoned amusement park, swamplands, and eventually the streets of New Orleans itself, where the military is conducting a final evacuation. Along the way, they rely on safe houses, improvised weapons, and each other to survive against increasingly dangerous hordes of the Infected.