What a lovely twist to the game. I was expecting a generic sokoban clone, but you took it to the next level. Ten next levels. Levels 4 and 8 in particular delighted me - 8 because it "got" me - I had a couple of minutes of "wait a minute, this is completely impossible!" and 4 because it was so elegant; it used multiple properties the elements beyond their obvious ones. It feels like a puzzle could be made where closing the door to push a character achieves something, but I can't figure out what. But in lvl 8, a door pushes two people (argh, didn't expect that! Thought it was a bug at first, since it was preventing me from finishing the level), so possibly it could push a whole chain...

Just bought the game today, and your level was the first one I played! Excellent from beginning to end. You should consider designing puzzles for a living! ;-)