Based on the classic series of PC games from the early 1990s, Commander Keen for the Game Boy Color offers players outer space adventures on Droidiccus Prime, Shikadi, and Fribbulus Xax. As eight-year old Billy Blaze, also known as Commander Keen, players can select easy (nine lives, nine continues), medium (seven lives, seven continues) or hard (five lives, five continues) difficulty settings and save progress via passwords awarded for the successful completion of each level. Beginning in the center of the Omegamatic Warp Drive, players are transported to worlds where they'll confront a series of challenges, including a Robot Hive, Fiery Canyon, Imperial Palace, Forest of Crazy Mushrooms, Plasma Crystal Mines, the Shikadi Overlord, Blooglet Lake, the Bobba Fortress, and a Techno Lab.More than three dozen unique aliens and monsters are divided between the three worlds, ranging from robots and poisonous slugs to plasma orbs, spiky Gik, and green-eyed, carnivorous Bloogs. Environmental level elements include toxic-slime, poles, blocks to shoot, switches, clues, and color-coded key doors. Commander Keen begins the adventure outfitted with his pogo stick for transportation and a Neural Ray Blaster for zapping enemies.The object of Commander Keen is to collect three plasma crystals, by defeating the final boss in each of the three worlds, in order to save the Earth from destruction. Extra continues are awarded for collecting a minimum number of items and power-ups (determined by the difficulty setting), with additional points earned by finding candy and snacks, batteries, mushrooms, water bubbles, fire extinguishers, small crystals, computer chips, rockets, and potion vials.