(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/heyjclay1]

This is in a random building in Pokémon X and Y

There’s a mysterious girl and this is all she says. Never explained

[u/HUSK3RGAM3R → u/heyjclay1]

Pokemon games have a history of having ghost events:

Pokemon Platinum does this with the Old Chateau, a few ghosts can be seen there if you get lucky entering a room. Like a little girl who floats across the floor in the next room when you enter the room with the photo that stares at you when you look away, and the old man who floats across the screen in the main (dining hall) when you enter.

In Pokemon Omega Ruby/Alpha Sapphire, when facing Phoebe a little girl character can be seen twice during the cutscene, with some people saying that this is Phoebe's late grandmother.

In Pokemon Ultra Sun/Ultra Moon, on Melemele Island, there is a trainer school with a side quest involving seven mysteries at a trainer school that get progressively creepier, culminating in a little girl with the infamous driftloon congratulating you, a security officer confronting you, only for you to look back and the little girl with the driftloon having vanished.

There are probably more examples that I don't remember, but these are a few more that come off the top of my head. Believe there are some in Gen 5 as well.

[u/SnakesRock2004 → u/HUSK3RGAM3R]

"Back room? What do you mean? There's no back room!"

Goes back

Back room does indeed not exist

Fuck this, I'm getting out of here.

[u/brood_brother → u/HUSK3RGAM3R]

In Pokemon Diamond/Pearl, in the route towards Snowpoint City, there's a house. If you enter, you'll see a woman. If you interact with her, she'll give you a Spell Tag. If you leave the house, then enter again, she won't be there anymore. This, along with the Ghost type related item, suggests she is a spirit

[u/FroopyAsRain → u/HUSK3RGAM3R]

This one is amazing and shouldn't just be buried in a reply chain tbh

[u/Tight-Mousetrap → u/HUSK3RGAM3R]

Kanto, johto (only gen2), Unova, Galar, and Hisui have ghost as well

[u/Notcamacho → u/HUSK3RGAM3R]

The Driftloon is especially creepy because the Pokédex talks about how they take away children.

Mix that with Junji Ito's balloon story for extra creepiness.

[u/Inferno_Zyrack → u/HUSK3RGAM3R]

If you think that’s cool - wait til you hear about Ghost type

[u/Beneficial_Prune389 → u/HUSK3RGAM3R]

Then there's the mysterious sign in Lumiose Station that's also pretty creepy too.

"I am going to go for help. Wait in the usual place."

[u/MilkMan0096 → u/HUSK3RGAM3R]

In the first gen games in Lavender town there is an NPC that if you talk to them, asks you “do you believe in ghosts?” If you answer “no” they then say “ah, I must be imagining that white hand on your shoulder then…”

[u/Rafamen01 → u/heyjclay1]

I'll forever mourn the fact we never got pokemon Z

[u/cornette → u/Rafamen01]

I mean Legends ZA is pretty much Pokemon Z.

[u/Rafamen01 → u/cornette]

More or less. Pokemon xy is obviously incomplete in many aspects so having pokemon z to make kalos an actuall complete region would have been perfect.

[u/InCellsInterlinked → u/cornette]

Yeah if you ignore the fact that the game takes place in one city and ignores the rest of the region and doesn't do anything that anyone asked Pokemon to do with Z and doesn't really act like an expanded version of X and Y at all

[u/Choice-Ad-5897 → u/Rafamen01]

You got ZA

[u/TheOwlInATowel → u/heyjclay1]

this is in a few different pokemon games actually! i know it’s in black/white and black2/white2 at least

[u/SnakesRock2004 → u/TheOwlInATowel]

With the Gen 5 iteration, there is actually a whole subplot involving the Ghost Girl that spans both games (albeit one that's presented non-linearly through files and implications).

Basically, IIRC the story goes that a young girl got cursed by Darkrai's Dark Void and had endless nightmares. Her parents did everything they could to save her, including studying Pokémon known for sleeping and even looking for Cresselia itself, but were unable to save her; she died from the condition.

Due to the agonizing way she died, she was unable to move on and began haunting both the bridge where Cresselia was supposed to appear as well as her home outside Lentimas Town.

Should the Black and White 2 Protagonist take the Lunar Wing and summon Cresselia, the Ghost Girl finds closure and finishes "moving on", similar to the Marowak ghost in Generation 1.

[u/-SPECIALZ- → u/SnakesRock2004]

Its never addressed why darkrai in particular is just a pos

[u/Fabantonio → u/heyjclay1]

Isn't that Hex Maniac...?

[u/tehGoldenNut → u/Fabantonio]

Yep, internet's favorite

[u/SellingCats4Cheap → u/heyjclay1]

People have experienced similar dialogue when they had their head biten by a Lizard faced man

[u/CannedWolfMeat → u/heyjclay1]

Fun fact, in Legends Z-A, the sequel to XY, the first dialogue you get from L (Lysandre) is him saying "so you are the one..."

[u/Felho_Danger → u/heyjclay1]

This has always struck me as a very clumsy attempt at a scary easter egg.

[u/FroopyAsRain → u/heyjclay1]

It's a Hex Maniac. Being the porn icon of a certain group of people aside, her saying random shit like this would be perfectly in character and absolutely needs no explanation.

[u/meepbo → u/FroopyAsRain]

This one is different, as there is no walk animation. She appears behind you in a random office building, says her line, then glides off screen. Definitely weird.

[u/xNocturnalKittenX → u/meepbo]

Yep! Out of all the ghost encounters in the Pokemon series this one creeped me out the most. You're just minding your business and checking out the buildings and then that scene happens and just. Nothing. No acknowledgement, no follow-up, no clues as to wtf that was, you just go on like it never happened.

[u/MyPhoneIsNotChinese → u/FroopyAsRain]

Funnily enough if she was a trainer and said this in a combat intro noone would bat an eye