Eight-year-old genius Billy "Commander Keen" Blaze has tracked the alien Shikadi to their ship, the Omegamatic, a galaxy-destroying weapon orbiting in deep space. To stop it, he must fight through its corridors, disable four protective machines, and reach the core. Armed with a raygun that stuns enemies and a pogo stick that launches him to improbable heights, Keen picks his way through a Custom cartridge, plug and play. Compatible: GBA, GBA SP, DS, DS Lite.