I tried the demo for a few minutes and found the basic puzzle mechanic pretty easy to understand without much explanation, which I liked. The underwater theme is cute too. My biggest suggestion would be adding more feedback when the player makes successful moves—animations/effects/sounds could make the interactions feel more satisfying. I’d also like to see the early levels tease more of how the gameplay evolves later, especially since the full game has 300 levels. The core mechanic works; I think making the moment-to-moment interactions feel more rewarding would help a lot.