1989-91 MS-DOS computer game series. Played today in the DosBox emulator. Reached its apotheosises with NETKEEN.

List of official commander keen games: Commander Keen 1: Marooned on Mars Commander Keen 2: The Earth Explodes Commander Keen 3: Keen Must Die! Commander Keen: Keen Dreams Commander Keen 4: Secret of the Oracle Commander Keen 5: The Armageddon Machine Commander Keen 6: Aliens Ate My Babysitter!