Soo it turns out that last year someone actually made a Keen related pinball after all (4 realz).
Mark1's Commander Keen:
In order to play it, you should first download and install Future Pinball from here:
http://futurepinball.com/
Then download the Commander Keen table from here. Extract it into the Tables subfolder of the game and then run it as administrator. Play the table. While in the game, '5' for insert coins, '1' is for starting the game, F1-F8 to change the camera.
I couldn't find a full screen mode though. The game is buggy and the whole editor kinda looks unfinished, but that's probably Future Pinball fault. Still, an interesting find.