You did a great job in finding a core gameplay element (the field of view / flashlight) and building the whole game on it, it felt really consistent. My favourite were DW weeping angels, it really did a twist on the "don't point your flashlight at stuff" priority once I realized they stop when I look at them, but raise my stress.
I also liked the visual style, very simple and readable, but still enjoyable.
Personally, I think you could put the short narrative and mechanical introduction in the beginning of the gameplay itself (with the option to skip it). On my first play, I went straight to playing the game and didn't even think about clicking on any other button in the menu, and ended up missing all the important information about my goal, my enemies, etc.