I really enjoyed this game. It was not too hard, not to easy and it remembered me the years I spend on Rolling Sky on my smartphone. 

I'm very bad at this game but it's super pretty and the controls are smooth (like ice) so I don't even mind. The few parts that I did get to were making great use of the subtle-ish mechanic of losing your path boundaries in the process of picking up crystals--nice theme adherence!

Impressive graphics! I like a simple light and dark theme. A nice challenge too, I could see it being a fun mobile game!