Beautiful game!
I do have to say, this game has something going for it! You did a wonderful job on this! Just one problem with it that could affect the longevity of it. There needs to be some challenge to it. Maybe some way to lose your ball, with a life system.. or a timer. Otherwise you can just go through each and each level without oppression, and there needs to be a little bit.
Suggestion- Maybe a practice course that has levels taken from the current Rumble Ball (Don't wanna see your hard work go for nothing! :D), then you can go to a competitive mode, to see if you can get the highest score without losing your ball!
in closing, this game is beautiful no doubt about that, gameplay is solid, just needs something to drive the skill of the player, something that needs them to take those critical shots.
Good going and good luck!