Good idea, and over all great. The puzzle design could be a bit better. Quite some times the same concept was repeated multiple times without any variation (see the introduction to reverse gravity). That tends to make uninteresting levels. Also the movement was too slow (at least at the start) and quite a few levels were easy to solve but unnecessarily hard to then complete. The reverse gravity + invincibility level springs to mind, as the window one has to press space is way too short.
But still an amazing enrty.