Way back in the early 90's id Software and publishers Apogee Software released Commander Keen for computers that used DOS. It was an incredibly fun platformer using EGA as a pioneer for the graphics at the time and shareware distribution. In Commander Keen you play as Billy Blaze, a young boy who travels through space and assumes the secret identity of "Commander Keen" while fighting the menacing alien race of Vorticons. An all time classic game, that is even more playable through Commander Genius which is a software piece that interprets the Commander Keen Invasion of the Vorticons and Galaxy series, with many new features and improved game play.