Here is some brainstorming.
Body horror was a strength of
Neverending Nightmares. Gore and unsettling transformations are good in horror games.
Giving players too much combat power just creates a scary action game. Survival horror works because ammunition is often so precious.
I watched a Let's Play of the
Call of Cthulu game for the first
XBOX. Players could bolt the doors behind them to try to buy more time to flee from the pursuing villagers. Dressers could be pushed to block doors or rope bridges cut to remove a path. Environmental interactions like that were lacking in
Neverending Nightmares.
Running could have realistic stamina where the character can last a few minutes before being winded.
Allow combat against enemy humans, but have combat ineffective against monsters such as the monsters only being incapacitated for a short time before regenerating.
Instead of physically fighting monsters, the environment could be used such as locking doors or raising drawbridges to create obstacles for the monster.
Instead of players controlling one protagonist, there could be a group that the player rotates control of. Killed characters could become enemies making the game harder near the end. The victory condition would be at least one ally character escaping. Completionist would be able to play the game for an ending where no ally characters died. This could be similar to a rogue-like with permadeath, almost like how people try to do
FTL: Faster Than Light runs with no redshirts.
Monsters could be instant death on contact, unless a player has the equivalent of
Last of Us's shivs. Those shivs would be a very limited resource and it might only temporarily blind the enemy.
Have an enemy monster that is invisible, but casts solid shadows. The player would need to use a flashlight or activate static light sources like kerosene lamps on a wall to be able to monitor the monster's location.
The 3D sound library would be good to use again for headphone users. 3D audio can be very effective.
The game could track completion time to facilitate speedrunners. The timer could be visible on the save file or displayed after the end credits.
It would be nice to have a gameplay goal other than survival. The game could be set in the gold rush era with the player character also having to pan for gold along streams while avoiding being eaten and scavenging supplies from dead miners. The ounces of gold could be used for people that like to achieve high scores. There could be
Donner Party trek scenario where the people before resorted to cannibalism to survive.
Cartography could be used as a gameplay element.
Longer games can be difficult to maintain tension. Perhaps the game could have partitioning, like how Five Nights at Freddy's has nights. At the end of each partition the player could be asked with a survey what they thought was real and what were hallucinations. The survey would impact gameplay based on how much the player mistook for not being real.
There could be ethical dilemmas with gameplay consequences, such as restraining a man to a chair before he transforms into a werewolf (Risking his escape later if another decision is made) or to make the decision to shoot him before he transforms. Instead of being pursued by one werewolf, the difficulty may be increased by the man becoming the second pursuing werewolf if he escapes.
There could be leveling down for character stats as described in
What if We Leveled Backwards?. Players would be forced to spend points to level down stats they choose. This can increase the feelings of helplessness over time.
The enemies could be towering overhead with their huge size. This would be like the tripods attacking in
War of the Worlds or the titans in
Attack on Titan. The player would be concerned about moving stealthily between one safe hiding spot to another.
There could a scenario where a flood of smaller enemies has to be outrun. It would be possible to kill individual enemies, but there would be so many that killing them all would be impossible. This would be like the
replicator battles in Stargate. Insect swarms make good enemies for such scenarios.
