Zero-5 is a shooter where players control the Perseus space fighter as a Space Hound recruited by DEFCON to defend Earth from the Morphon alien race in 2044. The Morphons detected and destroyed the Europa III satellite, prompting their invasion to eliminate humanity. Players engage in combat missions that require defending against and counterattacking the alien forces before they reach the planet. The title features 3D graphics and was inspired by the 1984 space opera film The Last Starfighter, though players without multiple disk drives experienced frequent disk swapping during gameplay.