Once I got a handle on what block orientation = button activating, I had a great time playing through each puzzle! It never felt like trial and error, which many of these games tend to fail at for me. The re-painting mechanic was really clever, the player might not even notice that pushing down a button 'erases' that color from the block until the RYB gate puzzle, but it's great how quickly that information is capitalized on. Smart, thoughtful design.
Clear graphics, satisfying sound, overall short but sweet -- I know you apologize for the lack of levels in the last stage, but I still felt satisfied after playing! Great work.