Commander Keen is a series of side-scrolling platform video games developed primarily by id Software. The series consists of six main episodes, a "lost" episode, and a final game; all but the final game were released for MS-DOS in 1990 and 1991, while the 2001 Commander Keen was released for the Game Boy Color. The series follows the eponymous Commander Keen, the secret identity of the eight-year-old genius Billy Blaze, as he defends the Earth and the galaxy from alien threats with his homemade spaceship, rayguns, and pogo stick.