Left 4 Dead is a first-person shooter in which the player takes control of one of four survivors. If human players are not available, the remaining survivors are filled by AI-controlled bots. They play through campaigns fighting off the infected—living humans who have been infected with a rabies-like virus that causes psychosis. The overarching goal is not to clear infected, but only to reach the next safe area alive. This is compounded by the presence of an “AI Director”, who tracks each player’s current situation, and will add or remove items & infected in response; with the goal of maintaining constant tension and creating a new experience with each playthrough.

To enable situational awareness of other Survivors, players are shown the health and status of their fellow survivors. If a player does not have direct sight of another Survivor (e.g. a wall is blocking their view of the others), they will be shown the Survivor’s highlighted silhouette. The Survivors are also susceptible to friendly fire, forcing players to exercise caution when shooting or swinging their weapons. As Survivors take damage, they move more slowly; if a Survivor’s health drops to zero, they are incapacitated and left to fight off the Infected using a handgun until rescued by another Survivor. If a Survivor dies, they remain dead until the next level, unless revived by a defibrillator, or, in Campaign or Singleplayer mode, reappear in a “Rescue Closet” to be freed by other Survivors. Should all Survivors die or be incapacitated, the game will end, at which point the players may restart that chapter or quit the game.

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 to be the spiritual successor to Left 4 Dead, as it is being developed by the creators of the original game, and features largely identical gameplay. The game was announced at The Game Awards 2020, and came nearly a decade after Turtle Rock Studios split from Valve (who published both Left 4 Dead titles and still owns the rights to the franchise) and re-established itself as an independent studio.