As they traverse the dangerous landscape before them, they have to use tools and weapons that they find to help them survive. The survivors are alerted to the existence of the last few remaining safe zones left on the coast and try to make their way towards these locations to hopefully find refuge against the ever-growing numbers of the infected. As they try to escape the city, dangerous mutations were developing in some hosts. Two weeks into the outbreak, 4 survivors developed an immunity against the disease. It's set in the aftermath of a zombie outbreak on the East Coast.

Left 4 Dead is a multiplayer survival horror game that was developed by Valve and was released back in 2008.