Nice little game.
What I really like is your character, a cute little feetless fire mage, and the physics. When I shot a fireball into the wind and it flew up it was pretty nice and interesting. I think this is a mechanic that should be used more often to solve little puzzles.
In general I think a puzzle approach could work really well for this game. The combat was rather easy, I just shot everything and didn't get hit once, but using the fireball was fun, although it could charge up a little faster. It's nice that the fireball is not just flying in a straight line, instead it acts like an arrow that gets pushed down again. I like that. Maybe do more with it. Random idea: make an enemy with a hit point on his back and the only way to hit him is by using the fireball physic because your are underneath him.
What I missed was more feedback like when I hit the spikes and nothing happens or a death animation. And you should give your fireball a light source to make a it illuminate a dark room a bit. It would be really cool in the level with the darkness when you shoot a fireball and you see what is around the fireball.
Overall nice game. Well done!