Overall I like it.
- An option to use the mouse as controller would be fun.
- On the main screen maybe show planets discovered as well as highscore and maybe move the highscore to a more obvious place (just to the right of play)
- Perhaps add an option to restart from the last planet with the current remaining time so you feel like what you have done before is locked in.
- I also think maybe make the trail thinner and add more detail to the sphere itself.
You may think I'm just being negative but I think you have a really good game here but it could be a great game. You have a lot to work with here and its making me look forward to trying out UE.