Very nice game! Good fit with the music, i personally got stuck at level 6, but it's pretty well made, i love how some of the levels, no matter your level of programming knowledge, will get you trying something at first, seeing it fail and then realise the actual way to do it, Great work!
XD I was quite happy with some of the level designs.
Yes, I believe level 6 is the first real tricky puzzle in the game. It gets more devious lol. I was surprised really at how a simple mechanic can produce really complex puzzles.
Thank you for your feedback!