Visuals: Game looks great, including models, textures, and shaderwork. A small exception when it comes to the obvious clipped look of the open part of the arm model and the outline shader sometimes looks bad at certain angles, like looking down some hallways and it catches the outlines of the stone wall. I also noticed further out the game looks grainy, unsure if this is a case of optimization or artistic vision.
Puzzles: Design seems about on point, it introduces concepts in a natural way that teaches the player what to do next if they're paying attention. The concepts are all well thought out and interesting to work with. One niggling thought is how one-way doors are used. They feel like windows sometimes and I couldn't tell at a glance whether it would open or not for me. This caused me to waste some time walking around checking them at times, and once made me walk to the beginning of the level since I thought there was a purpose to going back through the one-way due to it's virtue of existing at all. As an aside, I feel like your puzzles would be better if they had level names, though that's more a matter of taste I suppose.
Minor gripe is that the pause menu settings should probably be on the main menu.
Overall a fun 3D puzzle game. It took me about 45 minutes to an hour to beat it.