A good effort! Kudos on getting such nicely polished mobile interface out in a jam time-frame! We tried doing a Unity UI driven mobile game the weekend after this jam for Ludum Dare 40 and ended up giving up about 2/3s in (UI wasn't the killer problem, but it did take an extremely large amount of our time in that jam).
I agree with other reviewers' comments against the count-down timer... for a puzzle game it would be nicer to have a bit of time to think. Perhaps a better system in this case might be to rather give the player as much time as they want, but give them a star rating from 1 - 3 stars for each level based on how long they took (for eg. in 10 seconds = 3*, within 25s = 2*, longer than that = 1*)? That might also give some incentive to go back and replay old puzzles to get 3 stars.
I also found the difficulty curve a bit weird - it was easy going until I got to Swing (which I still haven't solved after 3 tries), then easy again on the larger ones, because they all seemed to use the same preset pattern for laying out the tiles.