The Cataclysm

Cataclysm is a hardcore PvE survival exploration modpack that revolves around defeating various bosses in a mostly linear fashion in order to progress through the game. Each boss drops their eye, and you will need to gather twelve eyes from twelve separate bosses in order to activate the new end portal in order to challenge a significantly fiercer Ender Dragon, all while mobs have the ability to dig, fly, and use many new weapons and tools to try and kill you in any way possible.

The bosses won't be your only challenge, as mobs have received a considerable buff in both their stats and their AI. Their damage, speed, armor, weapons, tools, and even intelligence will continue to grow stronger to match your progress, as defeating each new boss for the first time increases difficulty by a flat amount. Alongside a more hostile world, comes a limited life system where players start out with the soft maximum of three lives. Players can get up to a hard maximum of six lives, and also revive themselves after completely running out of lives, but only if the right preparations are taken beforehand!

But wait, there's more! Foods that are typically easier to obtain have received significant nerfs, making it more important than ever to explore the new crops, foods, and cooking methods which reward you with higher saturation foods. In combination with the food nerfs, players actively and passively lose hunger much faster now, constantly changing seasons make it harder to grow crops, and most farm animals take significantly longer to breed!
You will spawn with a guide book in place of the vanilla recipe book that will have similar information to what is written here, but reading both is recommended!

On your first day, naturally spawning mobs are locked to only spawning at the bottom of the world, and are not much of a concern as long as you stay away from caves, dungeons, and unfamiliar structures. Your starter bag gives you some food which is explained a little more in depth in game, but more food should be scavenged while you pick up other resources. After obtaining some wood, the easiest armors to craft on the first day are; Terracotta (made from clay), Basic (made from clay + leather) or Leather armor. Thanks to the mods Armor Curve and Armor Set Bonuses, these armors are very strong, giving you extra health, movement speed, and low amounts of armor now give far more protection than in vanilla. The first night will also be peaceful, because it is not until the second day when mobs can spawn during the night on the surface. By the second night, you should make sure you have solid shelter or be able to sleep through the night, because:

Mobs are very powerful thanks to Improved Mobs, Enhanced AI and IguanaTweaks Reborn, creepers will actively try to blast through thin walls to reach you or fling themselves vertically to reach you, most mobs will fly up to you if you are in a sky base, mobs will ride guardians to catch you in water, and they have many, many more tricks up their sleeves...

6+ GB of dedicated ram is recommended for this modpack.

Some boss music is provided by Scott Buckley via CC 4.0 license, his website can be found here.
Some boss music is provided by Makai Symphony via CC 3.0 license, their website can be found here. (V1.10+)

ONLY RELEVANT IN V1.01:
Some boss music is provided by Ethan Meixsell via the YouTube library.
Some other music credits are:
Andreas Zoeller for remixed Minecraft OST background songs.
Solunary for the Ender Dragon boss fight music.
Music in this modpack may get claimed if used in YouTube videos.

Art credits for custom item textures
(I haven't used textures from all of these packs, some are really cool and thought I'd share!) :
https://snoopethduckduck.itch.io/swords
https://alexs-assets.itch.io/16x16-rpg-item-pack-2
https://alexs-assets.itch.io/16x16-rpg-item-pack
https://opengameart.org/content/roguelikerpg-items
https://opengameart.org/content/kyrises-free-16x16-rpg-icon-pack