Keen Genius
If you don’t already know what Commander Keen is, don’t bother. If you do remember this game though, chances are you will love this. This is basically the old Commander Keen PC game packaged for Android. This includes episodes 1, 4 and 7. Other episodes can be added by copying them to the data directory (see app description in the play store ). This is based off of the shareware version of the game. The developer has a wiki page here: Keen Wiki