Main inspiration should be amnesia, slender and call of Cthulhu
Provide the player with objective to find objects that need to be investigated.
Their only means of interaction should be with the objects their looking for like Amnesia and Slender, Call of Cthulhu
This makes the player feel helpless, which is why both slender and Amnesia are scary
Have no attack, but maybe a kick to hold them back to allow the player to escape
The level should be dark, misty and only source of light should be the occasional light, moonlight and a torch.
Open space that are pitch black and multiple corridors of buildings so player is never quite sure what's around each corner
Possible make the torch occasional turn off at the worst moments
Open space player never quite sure what around each corner
Not all scare moments should be scripted a lot them need to be random and made by the player paranoia
The player doesn't come in contact with the hillbillies directly until they have got most of the evidence.
Like slender when player turns around they can see hillbillies moving and hiding in tree line or behind building progressively getting closer
their could be bits were the players knocked over and hillbillies run off putting player on edge
Its scarier if the player never directly See's them until certain build up moment or have so the player can hide from the hillbillies and escape them
could have screen distortions as the main protagonist losing his sanity