This is a lite 1.12.2 modpack (Less than 100 mods), runnable with only 3gb RAM allocation.
Despite it's smaller size, this modpack contains a whole lot of fun, with way too many mobs to count, things to explore, villages to conquer/build, and technology to master as you progress from your stone tools to power suits, godly weapons, guns, spaceships, and more.
A quick method for getting started: Cut trees for some wooden tools such a pic-axe, shield, and throwing spears. Mine stone for a stone tool upgrade. Look for structures that may contain routes into dungeons. Slay zombies and other mobs for gear and loot. Acquire some decent gear and start building up a base or village, utilizing various forms of technology. Protect it with golems/mob pets, guards, and more. Build up your power suit and launch base. If you can even make it this far, travel to the galaxies and beyond for further adventures!
Quality of Life:
Backpacks
Quark
Exploration:
--Mythical Monsters and Dangerous Dungeons
--Yung's Better Caves
--Recurrent Complex
--Rotten Flesh to Leather
--Craftable Saddles and Horse Armor
Survival:
-HarvestCraft
-Minecolonies
Mobs
Ice and Fire
Guns
Spartan Weaponry
Age of Weaponry
Vic's Modern Warfare Mod