I think there are some real design issues here. The game claims to be a puzzle game but the puzzles in it never made me think about how to beat them. The challenge in this game comes from figuring out how much energy something needs and then doing a somewhat tricky jump in most cases. A puzzle game should be about figuring out the solution to a problem and not exectuting it.
As a platformer I don't think it holds up because the movement is way too quick. All the levels are on one screen and there just is no reason to have the character move so fast. Also if you hold the jump button down, you keep jumping. I think that's an odd choice for a game like this.
When it comes to art, like may people here said already, the game looks gorgeous. The background is amazing and the character sprite is also great. I just think the progress bars on the objects could have used some better artwork as well.
I tried to play the bonus levels but in the first one I wanted to see if you could get stuck in the wall and well... yes. So I was kinda softlocked.
But inspite of the problems I have listed this is a great entry to the jam. The theme is well integrated and the setting overall is interesting.
I hope this feedback was somewhat useful to you.
Edit:
I saw you could select the level in the menu so I tried the bonus levels and I take back what I said earlier about not having to think about the solution. How do you beat level 14 ?