- The story of Back 4 Blood takes place after a catastrophic epidemic where much of the world's population is dead or infected by a demonic parasitic worm - A group of apocalypse veterans called Exterminators, hardened by unspeakable events and whose ambition is to fight for what remains of humanity, have allied to eradicate the infected monsters known as Infected and thus recover our planet - Back 4 Blood is a cooperative first-person shooter against zombies from the creators of the critically acclaimed Left 4 Dead franchise - It offers exciting and dynamic gameplay every second, as well as highly variable and customizable action so that players always come back for more - Back 4 Blood takes advantage of an adaptable AI called the Game Director, whose function is to monitor players' actions, health, and decisions in the background - As appropriate, it changes environmental conditions, adds obstacles, and releases special Infected mutations through card system modifiers called 'corruption cards'