Welcome!
Q: So what is the Underynth beyond issekai world?
A: The Underynth is an endless system of caves, tunnels, caverns and underground terrain that seems to go on infinitely. Some speculate its sort of like its own plane of existence as there's a lot of ambient magic that floats around causing all sorts of weird environments that normally wouldn't be possible like frozen pine forests and even oceans.
Q: That seems really convient, are you really just going to say "its magic" and use that as a pass?
A: Its magic, I don't got to explain shit.
Q: Is there anything else besides caves and magic weather?
A: Yes, there is civilization in the Underynth that go from small homesteads to fortified villages all the way up to bustling cities and multi-region states kingdoms and nations. By the time your characters appear, the Underynth already has a few thousand years of history and development behind it. Its not all the same and you can have two widely different tech levels next to each other, sort of like Rimworld.
Q: How does all of this work? Wouldn't it be hard to live let alone make a city in the Underynth?
A: Yes, but lucky for you, you don't have to figure that stuff out since generations of new arrivals before you already have. In addition, there are Mana Wells all over the places that have a habit of spewing stuff up depending on their size. Smaller ones might throw out materials or foodstuffs or other items while some can throw out new people, books and other things. The larger ones can even throw out vehicles. There are even many cases of entire buildings or facilities being transported to the Underynth through unknown means.
Q: What if I don't want to stay in the Underynth? Can I leave?
A: Out of character, yes. In character, no. There have been hundreds of thousands of attempts to get out of the Underynth including digging straight down, digging straight up, wandering and looking for a "surface exit", trying to use teleportation magic or jumping into a Mana Well. The mostly likely outcome for them are: returning tired, returning exhausted, maybe returning if you don't get lost, phasing into solid stone and instantly dying (if you are lucky).
Q: How does language work? Wouldn't everyone be speaking a different language?
A: As part of the magic of the Underynth, everyone can understand everyone else both speaking and written. Think of it as the magic automatically translating it to your known tongue. If you look at something in a different language you'll be able to understand it but you also know there's the feeling of the magic at work like a slight pressure or hum in your head.
Q: I have a question about the lore or how something works.
A: Then ask away and I'll answer as best as I can. While I probably have an answer for everything, I do ask that you suspend your disbelief at least a little bit. You are in an endless magical hell cave after all
Q: What kind of characters would we be playing?
A: Everyone would be playing a new arrival/"Arrivaler". You can play anyone you want but I would say it should lean towards more mundane and less Coldsteel the Shadow Hedgehog or Mr. Totally-not-Doom-Guy. You'll get your chance to get stronger and make an impact, its about the journey and not as much about the destination. Things like an orc office worker, a student at a magical academy, a spaceship engineer, a noble bastard turned knight, a wasteland survivor, a steampunk merchant trader, etc.
Alternatively, if you really want to start out as someone powerful then you can but you will be severely limited in your abilities if you even still have them. Your going from a level 100 Mafia Boss to a level 1 crook and starting from there again. There could be some interesting stories to tell with a character who no longer has their powers and everything that entails.
Q: Wow this seems really cool and you seem to have put a lot of work into this setting, I really want to be a part of this! Where's the CS?
A: If you're interested at all make it known below! A CS guide/requirements will be made once there's enough interest.
Ooo, I know an Inkarnate map when I see one! Been using Wonderdraft myself, but damn if Inkarnate isn't the more user-friendly to use.
Haven't done a group RP in a long, long time, but I could give this a shot if you'll have me. Thinking of writing a semi-comic relief character who has a completely different (wrong) understanding as to what's going on due to language differences. My idea is that his people only very recently settled in the north-east (~within 50 years?) and were formerly nomadic sea peoples raiding the coast.
@DegenerateThree, Not to be a pest, but settling implies that displacement of other people. Are they at war with the locals?