Love the pixel-art, the hammer looks really cute. I also like the combination of themes. Music was amazing too. Some critique:
As soon as I started the game, I was greeted by a welcome screen explaining the controls. This gave me a very bad first impression. Besides, the tutorial level already explained the controls in a fun interactive way.
One of the main points of this game is the Physics mechanic. I really enjoyed ground pounding to gain extra height. But overall, the movement felt wonky, especially moving horizontally in the air. It just felt really awkward.
And then I fell off the map. I expected to respawn at the beginning of the level, but instead I kept falling forever. From according to the description of your submission, I can assume that you knew about this: ```"...while avoiding falling into the endless void lying below all known reality."``` If this is a design choice, it is a really bad design choice. Honestly, go add a death plane.
Please don't be discouraged by all these negative things, there were a lot of things I liked about this submission. Just felt the need to point these things out.