This is a modpack that is meant to scare you. But, it is suppost to scare you throughout your gameplay as you also have some things to do in order to progress. Personally, I have been testing this modpack and playing it thousands of times and it has scared me horribly almost all the time. And if there is unknown errors or crashes, let me know please so I could possibly figure it out. Thank you and enjoy :)
Insanity Shaders(Recommended)- https://www.curseforge.com/minecraft/shaders/insanity-shader
Side Note: Also, make sure to turn on all the resource packs once you get in. Also if you want to play with friends, this modpack also has Essential in it so you could. Also if you want the experience to be way worse and your using the "Insanity Shaders" Go to Options>Video Settings>Shaders>Shader Options
Night Time:
Night Intensity:0.05
Night Ambient:0.20
Darkness:0.00(Complete Darkness)
Day Time:
Day Intensity:0.35
Fog&Atmospherics:
Fog Amount:8.50
Scare Craft
Horror Minecraft