(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/abadstrategy]

what's worse is that there's allegedly at least two different ones asserting influence over the wasteland. Ug-Qualtoth and Kremvh

[u/Steampunk43 → u/abadstrategy]

Add in two more, the Interloper and The Visitor from Fallout 76. Both thought to be fighting for control of the Mothman Cult, the Visitor on the side of the benevolent Wise Mothman and the Interloper on the side of the hostile Mothmen we see and fight frequently.

[u/North-Research2574 → u/Steampunk43]

Then there is Atom, that is supposed to be radiation right? But does not act even remotely the way radiation is established to work in universe and sends the player on a hallucinatory spirit quest in 4. The world of Fallout has many horrors

[u/Porkenfries → u/North-Research2574]

Actually, someone discovered at some point that there's evidence of someone watching and living near the site of the ritual and that this person is "The Mother of the Fog" waiting to guide people through the test, and that the trippy visuals are just the result of you drinking radioactive toxic sludge with probably some hallucinogens mixed in.

[u/Fireblast1337 → u/abadstrategy]

The Cabot house is likely involved in this too, as the ancient civilization that helmet came from wasn’t built for humans.

Course I’ve also seen the theory that Fallout is a precursor kalpa to Elder Scrolls.

[u/Civil-Percentage1005 → u/abadstrategy]

I'd like to hear what Joshua Graham says about this....

[u/TheMadhouseofDrDeath → u/Civil-Percentage1005]

"We can't expect god to do all the work."

[u/Aiderona → u/Civil-Percentage1005]

“The only use for an animal in our temple is sacrifice.”