Oh wow nice! A game that's theme around gravity sling shot, I've thought of using such theme too but I felt coding the physics will be too much for me to handle, so I'm glad to see a game using this theme!
I like the mechanic, takes some getting use to but it's enjoyable. Though I felt like the gravity is a bit on the strong side. Perhaps increasing the ships inertia and reducing the gravitational pull might make the overall feel much better.
Overall a job well done! keep it up!