A excellent game, and one I'd love to see a finished version of!
While balancing felt a bit strange here and there, I managed to get to the end of the demo without too much trouble.
One improvement I like to see is a gameplay tutorial. Right now, the tutorial does throw a lot of information at you at once. I think if all those abilities were introduced a bit slower, it would feel a lot more manageable.
Balancing issues aside, the game is lovely, and functions really well as a proof-of-concept