Back 4 Blood

Back 4 Blood is a thrilling cooperative first-person shooter from the creators of the critically acclaimed Left 4 Dead franchise. You are at the center of a war against the Ridden. These once-human hosts of a deadly parasite have turned into terrifying creatures bent on devouring what remains of civilization. With humanity’s extinction on the line, it’s up to you and your friends to take the fight to the enemy, eradicate the Ridden, and reclaim the world.

Left 4 Dead

From Valve (the creators of Counter-Strike, Half-Life and more) comes Left 4 Dead, a co-op action horror game for the PC and Xbox 360 that casts up to four players in an epic struggle for survival against swarming zombie hordes and terrifying mutant monsters. Set in the immediate aftermath of the zombie apocalypse, L4D's survival co-op mode lets you blast a path through the infected in four unique “movies,” guiding your survivors across the rooftops of an abandoned metropolis, through rural ghost towns and pitch-black forests in your quest to escape a devastated Ground Zero crawling with infected enemies. Each "movie" is comprised of five large maps, and can be played by one to four human players, with an emphasis on team-based strategy and objectives. New technology dubbed "the AI Director" is used to generate a unique gameplay experience every time you play. The Director tailors the frequency and ferocity of the zombie attacks to your performance, putting you in the middle of a fast-paced, but not overwhelming, Hollywood horror movie. Addictive single player, co-op, and multiplayer action gameplay from the makers of Counter-Strike and Half-Life Versus Mode lets you compete four-on-four with friends, playing as a human trying to get rescued, or as a zombie boss monster that will stop at nothing to destroy them.

Left 4 Dead 2

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.