(THANKYOU FOR 111+ (And now 233) DOWNLOADS!) This is the 1st Reason 2 Die mod pack.
Not 1, not 2, but 4 infection/invasion mods in the same modpack! Maybe 5.

BEHOLD:
From Another World
Fungal Infection: Spore
Sculk Horde
Prion Infection: Whispers From Within
Gigeresque
Zombie Awareness

WARNING: Avoid putting potion effects on the warden, as it will cause the game to crash.
The config files are changed so that most of the mobs from these infection mods will fight each other. Prion mobs attack the other mobs by default.

When creating a new world, it is suggested you use the Lost Cities world type to have a better apocalyptic experience.
There are 3 important village mods. Village Spawn Point makes you spawn at a village. Villagers are more competent with Guard Villagers and Golems Are Friends Not Fodder. You also have Starter Kit.

Updating the Forge versions and/or the mods themselves causes Minecraft to crash upon starting. Cannot update for now.

To survive an encounter with the aliens mobs (From Another World), a flint and steel is pretty much required. Later in game, you can craft a flamethrower. Epic.
Mobs from Spore and Prion are somewhat easy to take down depending on the mob type, but are easily deadly in swarms.
If you want to truly end your world, start a sculk outbreak by heading underground at coordinates 0, ~, 0 and trigger the sculk node inside of the Sculk Tomb. This will start the sculk infection and invasion. The Sculk Horde mod is for end-game and will ruin your world more than the other infection mods. Beware and be cautious.
Beware of Siren Head.

Before doing anything end-game however, you can experience getting to the End dimension in a new way with End: Remastered.
End Remastered in 100 seconds or less [Forge] (youtube.com)

On your journey, you'll find multiple structure mods to help the world feel populated and lively.

You also have backpacks, more farming, no phantoms, wall-jumping, more uses for copper, a use for rotten flesh, Ultimine, NO SLEEPING, and no swing cool-downs.
The Splash Milk is here to help manage negative potion effects, because there is going to be a lot of them. You can make milk bottles and their splash and lingering variants that will cure you.
Spartan Weapons and Spartan Shields will help with combat before you get your guns.
FYI, the undead don't burn in the sunlight and spiders crawl better.

Also, you can remove any mods you want. Be weary adding new mods because I don't know how compatible they will be with the rest. Adding new mods might result in a crash. Be sure to update the mods!
Please update the mods if the opportunity arises.

This modpack is named after an old Roblox zombie game called 'Reason 2 Die'.

I hope you have fun! Thankyou for your time. Now go out there and save the world of Minecraftia!

All mods and resource packs here do not belong to me. Every mod and resource pack here were made by their respective owner.