Very nice concept, and nicely executed! I was only able to survive a measly 200 seconds.
I don't know if it's intended or a bug, but the player seems to be able to refill their torch without needing a bonfire. If it's intended, I would have liked some sort of onboarding or indication that this was possible.
I might be wrong about this, but I didn't really experience any ambient sounds. I think I heard something from the rats, though. Some cave ambience would have added a lot to the immersion for me.