Planetoid is a single-player action shooter game in which players control a spaceship equipped with lasers and smart bombs, tasked with defending humans from alien attacks over a planetary landscape. In this game, players navigate their ship across a scrolling terrain, engaging in combat with waves of attacking aliens while avoiding obstacles and rescuing stranded humans. It stands out with its classic arcade-style gameplay, emphasizing quick reflexes, strategic use of limited resources, and precise shooting mechanics, reminiscent of the Williams arcade classic Defender.