Most of your screenshots seem to have the place at night. You mentioned light sources, too, however. How does the lighting work? Are there occasional hanging lanterns? Is the player capable of finding a torch or the like?
Players have a constantly-lit lantern at all times, and a pretty darn good one at that.
It has three settings: on, off, and bright. However, the only real way to survive is to hide, so you're not going to have it on all the time if you think the monster is nearby. There's another thing, as well: fog. As your sanity drops, ambient fog starts to fade into view. Because of the way Unity handles ambient fog, lights don't matter; it's just about distance. So, at some point your light won't help you see simply because your sanity is too low.
Incorporeal monsters aren't repelled by your lantern. Static light sources (braziers and the like, which do repel incorporeals) are scattered across the map at fitting points (for example, a clearing in the forest might have an old campfire pit).
It bugs me when horror games use constant pitch-darkness to scare players. It's frustrating having no idea where you're going, which hurts immersion. On a more personal level, it just feels kinda cheap. I've seen games that use darkness to great effect, but I've also seen games that prevent the player from seeing anything and call it horror. Ideally, it'd work out that, in this game at least, darkness is used occasionally, but not all the time.
That's a really impressive map.
Thanks!