It was fun and seems quite polished you got some good puzzles here.
At level 3 when you crouch, your character is clearly under the wall, I didn't saw the slide popup so i was confuse.
Also if you crouch near the wall you sligthly go under the wall even if your not moving, so you can "cheese" the level without sliding. I feel like there no need to slide, you could just make people crouch in this case.
Could be good to have a way to check for controls, like I missed the slide and drop popup at first, so i struggled to find how to do these actions.