This modpack prioritizes immersion, simplicity, and realism for an intuitive, more difficult overhaul that's not too overwhelming for newcomers. Everything is a resource here, and exploration is key.

The core mods are:

Complete mod list can be found under Relations->Dependencies

Key differences:

Tools are required to gather wood.
Flint and basic material TConstruct tools are all that are available before you get your first smeltery and create metal ones.
Water is naturally finite. (But you can conjure it with magic)
You need to stay hydrated.
Difficulty locked to hard.
You will die from starvation, thirst, hypothermia, and hyperthermia.
Health doesn't regenerate. (Use healing items such as healing salve, bandage, medikits, or magic)
You need a campfire/other Tough as Nails heat source or clothings to stay warm. You can also light your torches with it!
You start with a max health of 5 hearts, increased by life crystals found from within nether fortresses, up to a max of 20 hearts.
You can't create Nether Portals, instead, you'll need to explore to find a naturally spawning structure which houses them. To compensate, Nether Portals are immune to explosions.
Creeper explosions always drop 100% of blocks, and don't affect items.
There is a special dimension called the Teletory to be used for travel (1 block = 64 overworld blocks). However, you will take 2 hearts of damage constantly while inside unless you wear the special ender boots.

My advice for starting out:

Find flint from gravel.
Gather sticks by destroying leaves.
Craft a flint hatchet/axe.
Make a campfire ASAP, as you will freeze to death sooner or later without it.
Make use of the shields from spartan shields as well as armor.
Use Tinker's Construct to make weapons. Flint & Bone make for good early game materials.
Delve into the multiple magic mods. Craft their books and explore. Through magic, you can do things like heal yourself, negate damage done to you, and even cheat death!

Known Issues: I'm aware that Blood Magic's guide book doesn't appear in JEI, so here is the recipe. Sanguine Scientiem Recipe

Please leave feedback via comments or issues, it's much appreciated!

Immersive Survival