Great puzzle game! I was enjoying it very much, until a bug with the plant/rope took me to the top floor and I couldn't go back, later after I got the blue key it dropped out of existance. Anyways, on my second playthrough I liked it a lot.
I think I just got it too. If you have the rope and interact with climbing the plant, you cannot grab the rope without climbing up, and you can't climb down without dropping the rope, so you are locked out of using the rope elsewhere.