Pretty glitchy. The restart button wouldn't work on the first tutorial level.
The game assumes you know a lot of stuff that you don't. No tutorial explained the mechanic where you can fall through the floor if you jump through the ceiling first, so I felt kind of cheated when I had to use the walkthrough and it showed me an ability I didn't know I had.
Also, the first boss. The game freezes you when the boss shows up and then doesn't tell you that you can move again. So I sort of figured it was just a death cinematic and that I wasn't supposed to get close to the amulet fragment. And once you figure out that you're supposed to start running, you have no idea that you're supposed to jump on the worm's back. When I got to the first alcove, I pushed it sideways and then hid in it while the worm passed upwards. I was now stuck of course. But as the worm looped around, I found that I could hitch a ride on him by sort of glitching into him. I stood on his tail segment as he carried me up to the top of the screen, but I couldn't get further than that.
Games that use the mouse like this should have one-handed keyboard controls.
But what really kills this game is the lack of an undo option. You get stuck way too often when you're close to beating a level. You should be able to restore back to where you were when you entered a side of the cube, or undo the last rotation.
I love the idea and I love the puzzles. But this could've been executed better.