I would disagree with a detailed protagonist. Ideally the protagonist needs to be a blank slate so the player can project on to them. It also has to be vulnerable. A defenseless child is probably the most vulnerable character you can put in a horror environment in the mind of the player.
Games could do with taking some queues from internet creepypasta
That creature you have seen outside and appears to be getting closer to the glass? It's actually behind you.
Your friend finds a picture of a little girl making a peace sign with her hand. You find him dead later and the little girl is holding up three fingers.
Things like that creep humans out much more than jump scares or hidious beasts. Our own imagination can do a lot worse.
Slowpool and kane.malakos also make great points.
Games could do with taking some queues from internet creepypasta
That creature you have seen outside and appears to be getting closer to the glass? It's actually behind you.
Your friend finds a picture of a little girl making a peace sign with her hand. You find him dead later and the little girl is holding up three fingers.
Things like that creep humans out much more than jump scares or hidious beasts. Our own imagination can do a lot worse.
Slowpool and kane.malakos also make great points.