This is probably going to be unpopular but have actually scary things in your games, when I say scary I don't mean spooky ghosts or monsters, but things that you should genuinely be terrified of in real life. Look at this template:
>Green = Real and dangerous, can happen to you in real life and will hurt you or kill you, you should naturally be very scared of these things
>Red = Not actually real or no actual danger therefor you have no logical reason to be scared of it

Games like Outlast and Condemned are scary because most of the things trying to torture and kill you are homicidal psychopaths that exist in real life and even though the chance is rather small, it could technically happen to you.