Interesting demo, but needs a lot more work! I feel like the (presumably) 3rd party enemy models harm the game more than they help due to the mish-mash of styles (since they look semi-realistic, compared to the simpler and more cartoony environment). The level has a nice amount of looping and the glowing lava adds a nice little bit of atmosphere, though overall feels a bit flat and claustrophobic due to the low ceilings everywhere.
It took a while to figure out I was supposed to use the dash before jumping rather than mid-air. Combat was fine, but the enemy hitboxes (both for attacking and taking damage) didn't seem to match the models or animations. The range on the katana is very short and the spell book just feels like a worse pistol. Sadly, I gave up on the boss because his attacks were too hard to avoid and he had way too much HP. Still, good job getting the game out!