Interesting. I believe you still need to polish the mechanics better to solve some bugs (eg when the red ball goes through the cube wall). Maybe improving the way we control the ball and adding some mazes and obstacles will make it more interesting. Other levels could be different types of dices (like those used in tabletop rpgs, like d10, d12, d20). Your game has its charm, but it's still in the early stages of being a good game.