I really like it. Here is my 2 cent:

- the gravity is weird in my opinion. There is basically a gravity going down the screen. I would have expected there to be some "pull" towards the planets. I get why though, you try to prevent mega-long straight shots upward. Perhaps experiment with some drag, where the ball slows down over time. Or perhaps have the walls be gravity points, pulling the ball towards them.

- i would add a long- press to restart immediately, so restarting is faster.