Really like the graphics/art style and audio you have. The gameplay is solid, however I think it could benefit from some quality of life features. Displaying the percentage of crystals collected and giving the player a speed boost when leveling up would go a long way to ironing out some of the (admittedly minor) issues with this game.
I should also mention I found a few bugs. The first (and I'm not sure this is a bug) is that I got to the bottom of the cave without leveling up completely and still won. I don't know if this is a bug or if you have multiple endings though. The second is that you can grab crystals through walls.