I would rate this as the best puzzle game ive seen. The rolling around as a cube in a level and getting to the end was a theme that was quite often done and it really hinges on the quality of the twists or secondary mechanics. I think all your ideas really complemented the core gamedesign and it made for some very difficult but rewarding to solve puzzles. There werent many levels were I would just solve by trial and error but careful planning after a few firstexperimental moves. I especially like the implementation of picking stuff up from the ground and making things more complex that way.
A few nitpicks:
- The retry time is a bit too long for my taste - even though i eventually noticed the "r" button. I would make the restart much quicker in general.
- Some clipping sounds were a bit annoying but that might just be the webport.
- The movement scheme for the cube is not well suited for the more isometric view you chose. I would many times make false inputs because my brain forgot which direction was mapped to which key. A more straight view onto the level would easily solve that problem (it could still be slightly tilted).
Very nice Level/Puzzledesign i really enjoyed it.