I have no one to play this game with, so controlling both characters simultaneously makes my brain detonate.
I think the other comments say everything there is to be said about the string. I found it hilarious how, in level 5, both characters ramming themselves into the wall will cause the string to elongate out of the screen for kilometres. I was hoping I would have a giga slingshot when releasing the keys, but instead it just made it visually freak out.
This is secretly a rage game. The levels are very much on the hard side considering the unpredictability of the core mechanic and the absence of checkpoints.
I however think the idea is genius, I have not seen a game like this before. I think a version of this game where the string follows physics more accurately and does not go through walls would sell like little hot breads on the Steam market. Not to mention the art's minimalism yet consistency is both cute and immaculate.