It is recommended to add optifine to the mods folder to allow the use of the provided shaders
This modpack was meant to create a creepy atmosphere without relying on big changes to the base game while still providing a realism factor. Most of the mods in this modpack is to bring optimized gameplay and changes to bring that immersive experience like a revamped health system to include a factor of pain. There are two mods that can bring the normal Minecraft advancements to a halt by introducing to creatures that can really send shivers down your spine.
(below is what horror mods were used.)
The second mod will add a creature that lurks and will follow you throughout your journey in the deepest and darkest caves. Sounds that are known to be ambiance are emitted to lure you closer to its position until it has the chance to find you and kill you. [cave noises]

