What a delight! 3, 9 and 11 ended up being the real head-scratchers, for me at least. Particular kudos for 11 - it's always a sign of elegant design when a puzzle manages to conjure up a feeling of complexity bordering on impossibility out of a tiny level space.
The <spoiler> was a neat idea as well - if you're contemplating any post-jam revisions, I wondered if that bit could be made a little more difficult/different. (The finale of Jack Lance's Seasons puzzlescript opus has a mind-blowing approach to repeating levels)