Have you play tested your game fully?
I'm asking this because one of your puzzles is simple impossible. the Amethyst puzzle has 37 open ends and you need en even number to be able to connect all ends. (I hope that makes sens to you)
The concept itself is decent and works pretty good. It looks a bit simplistic though, make it a bit more appealing to the eye. and include a few more puzzles in the second category.
would have given it 8 stars, but having a puzzle game with a faulty puzzle is rather stupid. so your stuck with a 4.