Great game but it definitely needs more checkpoints. It gets annoying having to do the same parts over and over.
Maybe point out that the player can hide and turn off the torch so not to be seen? I did hide in a cupboard but the monster just kept wandering back and forth next to it until I eventually left and was immediately attacked. I actually found it easier to walk around in the dark (without picking up the torch at all) trying to find the way out.
It wasn't obvious what the button does. It sounded like a door had opened rather than it switch off the electricity (so you can input the codes). And when it moved I thought the game had a render bug rather than it being intentional.
Do the rocks do any damage? I tried to smash the monster with one but to no effect.
Although the monster reacts to the sounds, it doesn't seem to stop them immediately and it can still hurt you. Maybe also have an air horn but with only enough air for 3 uses?