Amazing for a first game jam entry! All of the elements (art, sound, music and game feel) really worked together very well.
The ice cube feels very slippery to move around, which feels great and the random rotation on some jumps was cute - the rotation just drove me insane on that last level where I had to do the jump up between two blocks twice.
The mechanic of leaving a block behind when melting worked very well as a mechanic - it just didn't make any sense thematically - if I melt there should be a puddle?! Maybe if I was a little CPU running around and overheated I would leave a block behind... :P