This is a lovely project!
It was really difficult to get into !
But after the 2nd level i kinda started getting the feel of it. But it was really frustrating at first. I think you should add some levels before, whjere the knot is not always there, maybe only in a part of the puzzle, so one can already learn to move 2 different characters, learn that you can jump on top of each other, etc... Your knot mechanic is really complex, so a player needs to master all the other mechanics before that or he'll loose interest because of frustration.
Other wise very good looking, intriguing, fun, puzzling ! congrats a very good game !