Pretty cool concept! In the long term, I think you'll have to decide if you want to make the game more physics-based and possible give players more freedom over the rotation or if you want to decouple the game logic from the physics. In puzzle games, I personally prefer if logic is decoupled from physics, but that's just a matter of personal taste. The UI could also need some polish, but the cube itself looks pretty nice already.
One more thing worth thinking about is giving the player a reason to care for what they do. That could either be turning the ball into some sort of character (see Hamsterball, for example) or add some other kind of story element to help the player connect to the game. I know that puzzle games are the one genre that can almost get away with just being completely abstract, but I still always like if there's some emotional connection that can be made to the game.