Back 4 Blood is a 2021 first-person shooter game developed by Turtle Rock Studios and published by Warner Bros. Interactive Entertainment. It was released on October 12, 2021, for Microsoft Windows, PlayStation 4, PlayStation 5, Xbox One, and Xbox Series X/S.
The game was advertised as a spiritual successor to the Left 4 Dead series, as it was created by some members of the team that developed the original game and carries over several key gameplay pillars, such as a strong emphasis on cooperative teamwork, and an AI system called the “Game Director”, which dynamically modifies the environment, placement of enemies, items, and obstacles in response to players’ progression and behavior.
In the game’s primary player versus environment game modes, players join a four-person team of post-apocalypse survivors called Cleaners, who must fight their way through levels populated by zombie-like monsters called The Ridden. Teammates are either controlled by other players or AI bots depending on matchmaking preferences and player availability. A new feature of Back 4 Blood is cards. At the start of each level, players need to build their deck with cards that adjust various elements of gameplay, such as modifying the player’s health, damage, and stamina. Along with player cards, the AI Director will also use Corruption cards against the player to hinder their progress. The AI can spawn extra enemies, activate a fog effect, and increase the size of the horde. The game features pre-defined hero characters who have preset attributes and abilities, and players can purchase upgrades and items with an in-game currency called Copper.
The game also has an eight-person player versus player mode called Swarm, where a team of four players assumes the role of Cleaners, and the other team of four control mutated Ridden. The teams are tasked with eliminating one another within a closed area.