Alien Swarm is a game and Source SDK release from a group of talented designers at Valve who were hired from the Mod community.
Available free of charge, the game thrusts players into an epic bug hunt featuring a unique blend of co-op play and squad-level tactics. With your friends, form a squad of four distinct IAF Marine classes. Plan your ...
Extermination is a campaign which unites these maps:
Midnight harvest 1 Midnight harvest 2 Arctic infiltration Area Cold catwalks Yanaurus mine Forgotten Factory Communication station Full Treatment - Syntek hospital