Very cute game! Couldn't finish it because at some point I went into the void and felt a bit nauseous after starting at tunnels for too long.
Another bug I encountered quite frequently is the tunnels being ever so slightly tilted in one direction. If this bug is active when entering a 2D portal, the tunnel looks very weird.
The procedural generation is impressive! But it leads to some areas where nothing happens, as well as some seemingly undogeable obstacles, especially in the 2D sections.
At one point, I got all seven yarn balls, but then hit a wall cause I rotated the tunnel instead of moving the cat. Oh well...
An awesome submission with a fun, creative idea. Good job!