It's not bad, but it falls a tad too slowly; also, when the balls stack up, they look a bit like they're floating in mid-air.
I see, thanks. There is actually one more thing I wanted to mention: it would be nice to have the ability to move left and right with the mouse. Also, regarding the red line—the one that ends the game if you cross it—I have a question: when we are holding a planet before launching it, the planet overlaps with that red line; it really ought to appear behind it. I hope I explained that clearly; my English isn't great, and since I used Google Translate, I might not have made myself understood.