Cool game. The gameplay is original, and frustrating.
The progressivity needs to be rethink. I suggest you to begin simple, with just one color and a basic level go to the end. Then add path, collectible, then add one more color (with the key on it please), etc...
It lack a bit of fantasy. For instance, it would be great to be on earth, destroying house/city/... with mountains (instead of wall), with some scoring system.
Overall that was fun to play, and with a bit of extra work could be even more fun.