A great mechanic for a clever, clever play on a cliche! The graphics are simple but effective. There's just the right amount of radiance to the light elements, and I love the little light charge up doodads. That design is just plain cool. Good choices were made with the pre-made sound assets, too. Nothing feels totally out of place.
The mechanic is such a good idea, and I love that the game didn't feel the need to hold my hand. It gives you the controls but lets you figure things out on your own (like pushing the boxes, etc). That agency made solving the puzzles so satisfying.
Also enjoyed the variance in jump vocalizations; that gave me a good chuckle, especially paired with how bouncy the knight sprite is. For what seems to be a one-man operation, this is a killer game.
My only suggestions would be to fiddle with the sound balance a bit and add some visual interest to the knight and the backgrounds. The light charging sound, for example, is pretty loud compared to the music. The backgrounds are also quite cavernous. Tossing some shapes and details in there just to mix things up would make a difference.