The mechanics were spot on for the theme, as I immediately understood what was going on, and the puzzles were fun.
A few points that felt frustrating: If you had two adjacent boxes, getting them to separate via the red area was sometimes quite painful. Also, I didn't see the point of the energy system. Were there any puzzles that required it, rather than a tedious increase in artificial difficulty?
In the level 3 you can soft-lock yourself in, which is bit bad.