This was inspired by Shivaxi's RLCraft, but with apocalypse in mind.
Features:
A possible new worldgen option, Lost Cities(I suggest "realistic" mode) - Lost Cities & Lost Souls
More structures - Rex's Additional Structures & Doomlike Dungeons
Guns, mechs, etc. - Flan's Mod and Content Packs
Smarter hostile mobs (can detect light sources, hear sounds, call for backup, form Skeleton Jockeys, etc.) - Zombie Awareness
Temperature and Thirst - Tough as Nails
Seasons - Serene Seasons
Storms - Weather, Storms, and Tornadoes
Better trees - Dynamic Trees
Crude weapons and warfare - Spartan Weaponry & Shields
And much more!
Any questions are welcome, might get back to you a bit late
Also, do not download Dynamic Surroundings v3.6.2.1- it crashes the game