Thank you for the feedback, and I'm glad you enjoyed the game! I know the one-button gravity-change game idea isn't new, I was going to go for a different type of one-button environment-change, but couldn't think of something good enough that I could keep small enough to finish. And I definitely get what you mean about the music - I was going to add more tracks (or make the track last a full minute without needing to loop), but I didn't want to risk going quantity over quality. I spend a fair chunk of time trying to make sure music sounds good before I add it to a game I make, and I didn't want to risk rushing the music and it sounding not great.
Not saying these are excuses, as I know I could've done better, but just providing insight into the development of the game. But I'm glad you still found the game fun overall!