Yeah. I mean, in truth, if you think of it, the fear of being alone in the dark is the fear of not trully being alone.
I also like the idea that sometimes you can't see things without being slightly "insane." So you feel something watching you, but you yourself can't see it. But that's just me.
It has that vibe I've been looking for since I watched Stranger Things. If I could give any recommendations, I'd say toy with the fear of the unknown. Keep things ambiguous but still have enough to make people curious/skeptical.