There is really little I can say here, except that it is a wonderful game.
The graphics are coherent and fit together stylistically well. Even if you have different biomes, you won't notice any negative effects by looking too weird.
The music reinforces the charm of the game and I only noticed it during the boss fight as too repetitive.
The theme of the jam you have solved relatively "standard", but you did it very well. The levels are detailed and it's not over after only 5 minutes.
The only negative thing that really bothered me was the controls. I hate playing with the arrow keys. In my opinion they have no right to exist in computer games. But that is probably just my personal feud with them.
Anyway, a great game.