Despite being stuck on level 16, I'm actually really enjoying this game! One thing I've noticed that I like is that up until this point, I haven't been stuck anywhere, and there have only been a couple situations I couldn't get myself out of before needing to hit the reset button. These levels have been really fun, I enjoyed bouncing around and phasing through things, and as always, the interface is pretty intuitive (with the one exception of the plus and minus signs, which I wasn't sure what they did until I used them). Nice work!