Play Commander Keen 1, 4, 7 and Dreams (Shareware) for free on your android device!
Episode 2, 3, 5 and 6 can also be played when you copy them to your data directory. You can get Episode 2, 3 and 5 on Steam. Keen 6 is harder to get (Ebay might help). Please consider that.
Those app downloads the shareware versions of Commander Keen episode 1, 4 and a mod called Keen 7 for you. You can also enable the HQP (High Quality Pack), which enhances music and graphics
About Keen 7:
Many Keen 1,2,3,4,5 and 6 mods are now supported.
Sources can be downloaded from the developers' Site.