A top-secret government laboratory experiment went wrong, and now invading aliens have infested the military base. Time to clean things up! Grab your weapon, recruit a friend, and start blasting wave after wave of alien scum into oblivion. Obtain more powerful weapons, battle against enemies of all sizes, clear each room, and eliminate the thread to the facility. Play a single player or co-op multiplayer campaign, and have a blast. Features: * 50 levels that can be played solo or with local co-op * Survival mode and boss rush mode * Top-down shooter gameplay * Multiple weapons and enemies * Multiple difficulty settings