Left 4 Dead

Left 4 Dead is a 2008 first person shooter developed by Turtle Rock Studios as Valve South and published by Valve, in which four survivors immune to a zombie outbreak fight their way across the eastern United States. The game's AI Director system adjusts the number and placement of enemies in real time based on how each playthrough is going, giving every session a different pace and difficulty. It established a cooperative shooter formula, sometimes called a Left 4 Dead-like, that later games such as Vermintide and Back 4 Blood followed, and it won Best Multiplayer Game honors from several outlets on release.