I think this is the best designed puzzle game I have played so far. I understand you where developing it solo so you may not of really cared about the graphics but clean up the graphics and it did take me a minute to realize that you can combine colors. the indicator at the top was not that apparent to me. If you cleaned it up a little bit and ad some more levels this would be a really great puzzle game. also, I really enjoyed that there felt like a little bit of a skill aspect when it comes to the movement.
Great Job!