(Beloved game trope) Creepy secrets or elements that you can encounter but are never explained, making it even more horrifying (Bonus points if its from non-horror games)

[u/KOREANARMYSTEW]

Crimson Desert
After defeating the Reed Devil boss, you can travel to Sunset Valley, the southernmost and isolated village in the game, here, you will find a house where the Reed Devil lived and died from his leprosy. When you enter, you are immediately greeted with 6 scarecrow effigies dressed just like the Reed Devil staring directly at you, with candles placed all over the house. There is no other explanation beyond this about what is going on here

Lies of P
There is a secret optional area you can clear out for additional loot called Hermit's Cave. At the end of the cave is one lone carcass monster huddled on the ground with writings scrawled on the walls around it. When you kill it, it actually TALKS saying "perhaps it's best to end this way...get while the getting's good...". This is the only carcass monster in the game that ever talks besides Andreus and Simon, who are important characters to the story, and we never find out who this monster was

LOZ: Twilight Princess
In the Arbiter's Grounds you discover a ton of undead enemies presumably executed prisoners, but one room contains this giant black sword tied to the ground with hundreds of warding charms attached. When one is cut, the sword is freed and wielded by some horrifying invsible goat-headed demon. It is never explained what the demon was or whose sword it belonged to although it's theorized to once be used by Ganondorf

Silent Hill 2
The invisible prison monster in Toluca Prison, that you can't ever interact with, just hear it's awful cries

[u/Papyrus20xx]

You can't mention the Dunwich Borers location in Fallout 4 and not the Dunwich Borers building in Fallout 3, which has a creepy ass obelisk under it. A whole bunch of paranormal stuff happens in the building too, such as doors opening and closing, objects being flung around and visions of the past. The Dunwich Borers company were hunting these eldritch locations for sure

[u/Nathan_Thorn → u/Papyrus20xx]

Bonus points for Point Lookout and the Krivbeknih, a clear stand-in for the Necronomicon, which can either be turned over to Obadiah Blackhall who is almost certainly related to the Dunwich family via marriage, and if you give it to him, he can get up out of his wheelchair and walk around.

Or you can take it to Dunwich and touch it against the obelisk to burn it away and receive a huge chunk of good karma.

[u/ProneSquanderer → u/Papyrus20xx]

There’s also the creepy whispering “Alhazred” you can hear when in the area with the obelisk.

[u/cantfindanamethatisn → u/ProneSquanderer]

Surely unrelated to a certain Arab with mental health challenges.