Some very tough puzzles here, but quite satisfying to work out a solution. Pretty bare bones presentation though - even a single musical track would have helped a lot.
Thanks for the feedback. I knew presentation was lacking; I'm not great with graphics or sound, worked by myself and just didn't have time to put sound in. But that will be something I plan around more for next time.
There's a lot of free sound tracks online that are alright quality. If it was me I would do a few less levels and spend that time adding feedback / sound instead.