Tip: Layer 3 backgrounds and tides disappear when you hit a message box, so plan your level around that. For example, you can add a sublevel without layer 3 at the start/midpoint, and include your message there.
It was fun but the levels aren't that interesting. Overgrown Forest was the best in my opinion. The question marks in the cave level are cutoff and after finishing the Castle there is a level tile leading to an endless bonus game.
Also, did you seriously replaced any black color in the game with purple? It doesn't look better then.