You thought RL Craft is hard. Think again. In this modpack if you go to far and make one mistake even at the middle of the day. It can end your life easily. Days are short and Nights are long and harsh. Unseen horrors emerge to the surface that will make everyone wise enough run to the nearest shelter. You can punch trees and you have fancy weapons, but food is greatly limited and options mostly aren't changed from vanilla. Also weather system is much more realistic and sends storms to your house regularly and they can even destroy everything you worked so hard for. Temperature and hydration will also become your priority while your enemies won't have such problems. Also your parts of the body have separate health so if you take only 3 hearts of damage in you are done for (unless you have a good helmet). You can use books provided on start of the game to you to ascend and progress but guard them carefully because if you lose them you are lost man in this hell and you have to craft them. You can go to village which can be very far away from your spawn and it is carefully guarded by guards that will chase you or kill you if you steal loot, crops or hurt villagers. And there are many more things to worry about like dragons that are more common around village (i think), they are fast when chasing and encounter with them can lead to death 100% of the time with primitive gear and without strategic knowledge and your knowledge of advantages in this place or agility and constant running. And we are just getting started. There are much more stuff to worry about in this modpack that is explained in more details in spoiler mod descriptions. And yes add Optifine F5 unless you want heavy lag spikes or other performance enhancing mods as you wish.

Importance of biomes in this modpack:

Biomes in this modpack are more than patches of different vegetation and elevation, most of the mobs in this modpack only spawn in certain locations, making some places much dangerous than others, Eg. jungles and swamps are one of the most dangerous (at least at night) while ocean is also dangerous but plains seem to be a bit safer but almost every biome is dangerous except mushroom island which is ultra hard to find so good luck. I might check about danger of biomes. Also some biomes are hotter and colder than others but that is obvious and rest of the things you can find yourself, maybe i will make basic tutorial what you need to do, but other than that you are on your own.

Ultimate hellish nightmare simulator