Dude, the atmosphere is soooo good! I love the setting, the writing and the exploration. Also had one hell of a scare when I died after recklessly traversing back to a previously discovered spot while completely forgetting the zombie in there. hahaha
The main issue I had was with controlling the flashlight. I was using WASD for movement and the mouse for the flashlight, but couldn't seem to point it to where I wanted, so I would just slide the mouse left or right until it stopped kinda in the place I wanted and then rolled with it until the corridor changed direction. One specific issue is that it stopped computing mouse movement if the cursor went outside the game screen. I would personally prefer one of these alternative control schemes: seeing a stylized mouse cursor in game and the flashlight always pointing to it; or the flashlight always rotating counterclockwise or clockwise if I drag the mouse left or right, while ignoring vertical movement and working regardless of the (then invisible) cursor position (a bit quirkier, but one could get used to it and it could double down as a quirky, RE1-style car control gun aim), or even the flashlight always pointing to the character front, perhaps with some angle interpolation just for polish and extra suspense.
Ah, another minor hindrance was the floor and wall having such similar colors, making it a bit difficult to understand the collision boxes for the labyrinth.
These were literally the only problems I had, and I'm VERY curious to finish the game later and see the rest of the story! The ambiance is just fantastic! I can also definitely see the potential for a commercial release, if you want to expand on it :)