This game is something.
Achievements are a great addition to the game. Story is mystic and music fits well. Standard platformer mechanics are very well done with the animation of the cube, good job!
The only thing I don't like is the flying level. It's hard and I stopped there because couldn't get passed it. And flying seams off to me, it doesn't recognize every click somehow (either space or left mouse click). Is that the last level?
btw. Sound of cube re-spawning is just like a steam message so it messed with me for sometime :)