From GameBrew - a wiki dedicated to Video Game Homebrew.
CommanDS Keen is an adaptation of a series Commander Keen on PC. It is an adaptation, originally open source software named CloneKeen Caitlin Shaw.
This adaptation can play the episodes 1, 2 and 3 (only episode 1 is available as shareware and integrated into this adaptation).
Keen has crashed his ship and has to recover the parts needed to make it work and go home. Advance through the enemies and obstacles to access the next area.
D-pad - displacement
A - shoot
B - jump
L - menu exit
A - menu save