Back 4 Blood

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 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 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.

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.

In the primary game modes, the player can control one of 12 Cleaners: Walker, a United States Army Ranger veteran and de facto leader of the Cleaners; Chris, the eldest Cleaner nicknamed "Mom" because of her maternal attitude; Holly, a brash fighter who wields a baseball bat named Dotty; Evangelo, an optimistic recruit; Hoffman, a socially awkward survivalist and conspiracy theorist; Seo-yeon, who is nicknamed "Doc" for being the group's medic and scientific expert; Jim, an experienced hunter and marksman, Karlee, a cynical lone wolf, Heng, a survivalist and chef at heart, Sharice, a tough as nails former firefighter, "Prophet" Dan, a protector for "the light's chosen", and the newest cleaner, Tala, a former cult member of the children of the worm.

Back 4 Blood was developed by Turtle Rock Studios, including seven of the developers who worked on the demo that became Left 4 Dead. According to the development team, Back 4 Blood features a more expanded story than the Left 4 Dead games, and has a more uplifting tone than other zombie games. Phil Robb, the game's creative director, added that the Cleaners are more confident and capable, unlike the everymen from Left 4 Dead. The team included the card systems because they felt that it can keep Back 4 Blood dynamic and challenging for veteran players; Turtle Rock added a Classic mode, a more accessible experience that removes the cards, for new players.

Back 4 Blood was announced in March 2019 by Turtle Rock and publisher Warner Bros. Games. It was unveiled during The Game Awards 2020, with the closed alpha releasing December 17, 2020. Initially set to be released on June 22, 2021, the game was delayed to October 12, 2021 for PlayStation 4, PlayStation 5, Windows, Xbox One, and Xbox Series X/S.

Back 4 Blood received "generally favorable" reviews for the PC and PlayStation 5 versions but "mixed or average" reviews for the Xbox Series X/S version, according to review aggregator Metacritic. Fellow review aggregator OpenCritic assessed that the game received strong approval, being recommended by 71% of critics.

Neil Bolt, writing for horror magazine Bloody Disgusting, said that "the game still often plods along casually for periods before unleashing far too much confusion and chaos at once", adding that "given the game this is trying to build upon, seemingly random encounters make sense, but there needs to be a level of puppeteering behind the scenes to ensure its not a mess in play", with his conclusion being that Back 4 Blood is "almost unpleasant to play at times" but that it was a "decent" game. Polygon cited it as the 47th best game of 2021.