Hey, thanks making the build! I just played through all the levels and here are some thoughts:
Really neat little game, very polished for the time limits of the jam. For most of the levels I thought the controls worked pretty well and I could mostly get the box to do what I wanted, however there were a couple levels like 1-4, and 2-3, where I really couldn't get the jumps to happen consistently and found myself flailing about with the mouse until the box just randomly got to the end. Also, as for the structuing of levels. I really like how each new set of levels you introduced new mechanic, and then the mechanics started to layer on each other. Really good on boarding there. But was there a reason water was the last set of levels? I found the lava that came right before it much much harder than the water levels.
Anywho, really great job!