Great demo! I've been listening to your podcast so it was nice to finally see all the things you were talking about :)
While playing I kept wishing for a shield of some sort, or being able to shoot at the fireballs as a form of defense.
I got to the baby dragon boss, and while it's very challenging with the slimes and everything, it felt like the charge attack was too slow and often didn't aim at me at all. If the charge attack is made faster, maybe make it wait until there aren't many fireballs on screen though. I had a lot of fun playing the demo, great work!