Nice little game, with a simple but coherent style. I'd just tune friction (many many times the ball stopped rolling just before reaching the flag... let it roll more or give players successive shots, with par system maybe?), and hitting power: in browser I had an hard time to transition between moon because I couldn't drag the cursor far enough.
The graphic at first seems as simple as it gets, but it can grow on you creating a relaxing experience, despite interrupted roll frustrations. The rocket zooming in at the start and the little astronaut following the ball from shot to shot are a really nice touch.