This is incredibly creative! You finished just below me in the jam! How this didn't finish in top 10, and how you actually finished a game that looks and plays this good is beyond me. The art is beautiful, and the mechanic is very well done, I though about rewinding string actually, but ended up not doing it :P. The only things I would change, is the fact that I move slower in the air than on the ground, it made jumping feel awkward, (not saying that it sucks) but check out this video on how to polish up the movement a little more https://www.youtube.com/watch?v=vFsJIrm2btU&t
Next, the buttons in the background kind of blend in with it, which is good so that they don't look strange, but it took me a minute to see them, so maybe make them stand out more. And finally, I didn't like using F and S for the rope, it felt awkward for my fingers, maybe S is fine, but maybe use E or something, or let the player change it manually.
Great job with this!