Excellent game! All that's really wrong with it is that it needs more level :-) I found that the shift key to unstick feature didn't impact gameplay much; it was much easier to just never be all one color and control stickiness entirely by spinning. If you removed that mechanic, it could open the door for additional mild puzzle elements as you could force the cube to take a solid color (maybe passing through a waterfall of paint?) on entering a section and the player would have to contend with an inability to move without jumping until you give them a different colored paint puddle so they can get out of monochrome hell.