Make sure you use the lost cities world generation option there may eventually be a quest book added currently there are a large selection of horror mods added and more to come ranging from SCPs, Demons, parasites and even your favourite horror movie KILLERS! if your looking for everything spooky you have certainly came to the right place :)

SCP Foundation
Demons from Doom and Lycanites Mobs
Deadly sins
Disgusting mutants
Foul beasts from Bloodborne

VIDEO IS FROM THE 1.12.2 VERSION THIS VERSION IS HEAVILY ALTERED DUE TO DEAD MODS AND NEW ONES :)

MOD LIST:

Presence Footsteps [Forge] (by Paint_Ninja)
Odd Water Mobs (by jocosero)
Blood And Madness (A Bloodborne Inspired Mod) (by Nitespring)
Eyes in the Darkness (by gigaherz)
AutoRegLib (by Vazkii)
AppleSkin (by squeek502)
Ultimate Car Mod (by henkelmax)
Bountiful (Forge) (by Ejektaflex)
Fish's Undead Rising (by fish0016054)
Konkrete [Forge] (by Keksuccino)
Horror Elements mod (by predator97427fr)
SwingThroughGrass (by exidex)
Necrum! Devil's Request (by pixelgeist666)
Polymorph (Fabric/Forge/Quilt) (by TheIllusiveC4)
Dusk[Forge/Fabric] (by someaddon)
Structure Gel API (by ModdingLegacy)
Werewolves - Become a Beast! (by Cheaterpaul)
Puzzles Lib [Forge & Fabric] (by Fuzs)
The Lost Cities (by McJty)
Waystones (by BlayTheNinth)
CoroUtil (by Corosus)
Enhanced Celestials - Blood, Blue, & Harvest (Super) Moons (by Corgi_Taco)
Scary Mobs And Bosses (by ALe96)
Bookshelf (by DarkhaxDev)
Zombie Awareness (by Corosus)
Scuba Gear (by ModdingLegacy)
Patchouli (by Vazkii)
Mouse Tweaks (by YaLTeR)
Vampirism Integrations (by maxanier)
Macaw's Bridges (by sketch_macaw)
TRansliterationLib (by tr7zw)
IntoTheVoid (No updates planned) (by Unusual_Squad)
Epic Knights: Shields, Armor and Weapons [Fabric & Forge] (by magistu_)
FancyMenu [Forge] (by Keksuccino)
ToroHealth Damage Indicators (by ToroCraft)
Blueprint (by TeamAbnormals)
Pam's HarvestCraft 2 - Food Extended (by pamharvestcraft)
Xaero's Minimap (by xaero96)
SCP: Overtime (by gus)
Human Companions (by jus10wontons)
Moonlight Lib (by MehVahdJukaar)
Cloth Config API (Fabric/Forge) (by shedaniel)
Obscuria's Tooltips (by Obscuria)
Corail Tombstone (by Corail_31)
The Legend of Herobrine (Forge 1.16.5) (by AlexMacLean)
Cyclops Core (by kroeser)
Colds: Lurker (FORGE) (by Coldspell_Games)
CreativeCore (by CreativeMD)
FTB Quests (Forge) (by FTB)
Astemir's Forestcraft (by Astemir_Kerefov)
Abyssal Depths (by Chumbanotz)
AmbientSounds 5 (by CreativeMD)
Auudio [Forge] (by Keksuccino)
iChunUtil (by ohaiiChun)
The Cursed Realm 2 (by Molten546)
Architectury API (Fabric/Forge) (by shedaniel)
Doctor Who - Weeping Angels (by Suff99)
Pam's HarvestCraft 2 - Crops (by pamharvestcraft)
FTB Teams (Forge) (by FTB)
MCDoom (by AzureDoomC)
Upgrade Aquatic (by TeamAbnormals)
Undead Expansion (by Fredzik2)
Spiders 2.0 (by TheCyberBrick)
EvilCraft (by kroeser)
Pam's HarvestCraft 2 - Trees (by pamharvestcraft)
Wandering Bags (by Furti_Two)
Better Burning (by DarkhaxDev)
FTB Library (Forge) (by FTB)
Lycanites Mobs (by Lycanite)
Citadel (by sbom_xela)
Levinide (by TrueRealCursed_Warrior)
Mutant Wolf (by TrueRealCursed_Warrior)
Hwyla (by TehNut)
Combat-Commons (by Elenterius)
Mantle (by mDiyo)
Vampirism - Become a vampire! (by maxanier)
GHOSTBUSTERS Mod (by WYLDDOGLIVE)
Regrowth (by MacTso)
Tinkers Construct (by mDiyo)
Obscuria's Essentials (by Obscuria)
THE UNDEAD REVAMPED (by punpanprolol)
GeckoLib (by Gecko)
The Conjurer (by ModdingLegacy)
Horror Movie Monsters (by ApemanMC)
ExpandAbility (by florensie)
Paragliders (by Tictim)
Dark Paintings (by DarkhaxDev)
Guide-API Village and Pillage (by maxanier)
Doggy Talents (by percivalalb)
Good Night's Sleep (by ModdingLegacy)
The Graveyard (FORGE) (by finallion_13)
Dynamic Surroundings (by OreCruncher)
Valhelsia Core (by ValhelsiaTeam)
Fast Leaf Decay (by olafskiii)
MrCrayfish's Gun Mod (by MrCrayfish)
Mutant Beasts (by Chumbanotz)
Alex's Mobs (by sbom_xela)
Project Fright (by Decyphvr)
Whisperwoods (by itsmeowdev)
Bones (by ochotonida)
Curios API (Forge) (by TheIllusiveC4)
Audio Extension for FancyMenu [Forge] (by Keksuccino)
Aquamirae (Forge) (by Obscuria)
ConnectedTexturesMod (by tterrag1098)
Obscure API (Forge) (by Obscuria)
Drop the Meat (by platinmoralle)
Biomancy (by Elenterius)
Obfuscate (by MrCrayfish)
Toad Terror (by Cicoda)
Nyf's Spiders (by theNyfaria)
Item Filters (by LatvianModder)
Sons Of Sins (by Furti_Two)
Kotlin for Forge (by thedarkcolour)
HT's TreeChop (by hammertater)
Better Third Person (by Socolio)
Froglins (by Commoble)
Xaero's World Map (by xaero96)
Clumps (by Jaredlll08)
Occultism (by kli_kli)
Pandoras Creatures (by andrew0030)
Stalwart Dungeons (by Furti_Two)
Dungeons Plus (by ModdingLegacy)
Pam's HarvestCraft 2 - Food Core (by pamharvestcraft)
Zonko's Monsters (by TheRealZonko)
Simple Planes (Forge) (by przemykomo)
The Five Nights at Freddy's Mod (by Mephilis)
Old Mutant More (by alexandersfunandgames)
Rotten Piglins Mod(Forge) (by abukkezsaruj)
Rigoranthus Emortis Reborn (by PlatinumG17)
Just Enough Items (JEI) (by mezz)
Mob Sunscreen (by Kreezxil)
Mowzie's Mobs (by bobmowzie)
Just Enough Resources (JER) (by way2muchnoise)

NightmareCraft Resurrection

Abyssal Depths

Alex's Mobs

AmbientSounds 6

AppleSkin

Aquamirae [Forge Edition]

Architectury API

Astemir's Forestcraft

Audio Extension for FancyMenu v2 [Forge]

AutoRegLib

Auudio [Forge]

Better Burning

Better Third Person

Biomancy

Blood And Madness (A Bloodborne Inspired Mod)

Blueprint

Bones

Bookshelf

Bountiful

Citadel

Cloth Config API (Fabric/Forge/NeoForge)