A nice little puzzle game. I'd have liked some background music and perhaps a level select screen, but I know that's probably not a priority in a 48 hour jam! I think the difficulty could probably have ramped up a bit earlier, but I play a lot of puzzle games so maybe someone less familiar with them would appreciate how incremental it is.
I'm curious about how you went about designing the more difficult levels. Did you work backwards?
Also the Foleyship would be proud of that ice melting sound effect! :P