I had a hard time getting through the last level. The cube wouldn't fit in the black hole, and I still don't see the utility of the second wall. Cubes are also surprisingly light, and covered in soap, but I admit that makes them fun to play with!
Still cool to see a first person puzzle! And despite some of the physics issues, the engine seems to work well. There are potentials with these mechanics, especially the idea of an impulsive and a repulsive portal.