Back 4 Blood is an online multiplayer first-person shooter game developed by Turtle Rock Studios and published by Warner Bros. Interactive Entertainment. It was released on October 12, 2021, for Windows, PlayStation 4, PlayStation 5, Xbox One and Xbox Series X/S. The game has been considered the spiritual successor to Left 4 Dead, as it was developed by the creators of the original game, and features largely identical gameplay. A parasite called "the Devil Worm" (implied to be of extraterrestrial origin) infects most of humanity, turning them into vicious undead mutants called the "Ridden". One year after the beginning of the outbreak, pockets of humanity attempt to survive in the post-apocalyptic world. A group of veteran survivors called the "Cleaners" fight the Ridden and defend Fort Hope, a settlement within fictional Finleyville, Pennsylvania, United States.