Nice horror game. Really good work with the shaders and environment overall.
I don't know it that was the intended experience, but I managed to complete the game only by running from a safe room to the next. At some point I choose to jump down from the balcony rather than running down the stairs because I thought it was quicker and safer, and that means the level design was good. I was also spamming the echo to find where the monster was (I used an instrument because I didn't want to use headphones). I was using linux and didn't encounter any audio problem.
The monster behavior felt too random, trying to enter a room for too long and seemingly teleporting in random places. I think I saw once two pairs of eyes, one red and one white? But I think there is only one monster in the game so maybe it was a bug.
Losing was a little too frustrating because of the randomization of item placements. In horror games the fear of loosing progress is more important than actually loosing progress. For example I'm okay with the random position of the code because the places where it could spawn are obvious and knowing them is progress that's not reset.