I like the concept of the game, and the graphics were stunning! It took me awhile to figure out exactly how to play, since there were no instructions, but I eventually got the hang of it. I noticed the progress bar of the planet was rotating as the planet rotated. It felt unnatural that way. One way to fix that might be to rotate the planet mesh only and not the widget. I also noticed the high score button was not working after I had returned to the main menu.
Overall though, I had fun playing, as it was such a unique idea!