Slymoids is a single-player action, shooter, casual, and arcade game in which players defend against waves of enemies using a gun, shooting both airborne and ground-based foes. In this game, players take on the role of a cowboy fighting off the Slymoids, who approach from the horizon and the sky across three distinct locations: the coast, the city, and a cavern, each with unique environmental challenges like falling stalactites in the cavern.