 Overkill Software, the developers of "", a similar game to "Left 4 Dead" featuring four player co-operative gameplay, announced in June 2012 that it has worked with Valve to create a DLC level for "Payday" in the form of a map mirroring the "No Mercy" level from "Left 4 Dead", however, this DLC level is not canon to Left 4 Dead and does not lead to the infection that initiated the events in "Left 4 Dead".On August 20, 2015, an update for the game "Zombie Army Trilogy" was released, which imported the eight survivors from both "Left 4 Dead" games into "ZAT".The original development studio behind "Left 4 Dead", Turtle Rock Studios, announced a new IP in March, 2019 that is a spiritual successor to "Left 4 Dead" titled "Back 4 Blood".