Awesome game! I liked the way the map opened up as I got skills, and how each area was clearly separated by the skill yet to be acquired. I got stuck one time where I put a skeleton on top of a button and then I couldn't get a crate to the button (I was trying to see if skeletons triggered buttons XD) It got me locked but the music got me hooked so I didn't mind to restart and keep going.
Also the areas are interconected in an interesting way, and I liked that once I got through an area, I could make a short path available to it. In general very good levels and puzzles. I did save the cat <3