I know it's been a while since I finished writing The Soulforged Dungeoneer. If you haven't read it, I suggest starting there - it is strange and sometimes quite silly, but it establishes a lot of canon that will make the rest of this make more sense.
For those who have read it, here are the highlights.
Jerry Applebee lives in a System-invaded world, where Dungeon portals popped up all over the world, which seem to be managed by Administrators - all of whom used to be mankind's nightmares, distilled from ghosts and spirits of the world that were sucked up by the Labyrinthine Star, a massive stellar fortress that seems to be passing by and testing civilizations as it goes. Each Administrator is partnered with a Dungeon God, who seem to have some advisory role. Unlike Administrators, Gods are inherited from the previous world that the Star visited - at least, at the start. (There is also something about Seven Sovereigns with weird titles who seem to be in charge of things, including the Fool, Saint, and Artificer, who are also from the last visited world.)
Those who dive into Dungeons - now called Dungeoneers - gain System bodies and classes that come with a variety of benefits, and the world is slowly adapting to their presence, even if it is not yet understood. Like... at all. Jerry's Soulforged class is self-created, and there are various hints that the whole system can be more freeform than it initially appears, but details are sparse. The book never touched on topics like changing one's class or multiclassing, though you have the ability to alter what you get at level-ups if you try hard. There's also something something Cultivation where you burn experience to alter your body without leveling up.
Starting from a place of ignorance, Jerry, a "solo diver" who cleared a Dungeon alone, meets a Priestess (all of whom can detect lies), Louise, who becomes his girlfriend. He gains a Fairy companion, Merry, then quickly gets tangled in politics because fairies are supposed to somehow steal secrets from the Star. In the process, he's forced to promise that he'll try to defeat Bo, a solo diver who dived into "fairy dungeons" and got his name and soul stolen by a Fairy Queen, who forced him to take over a section of dungeon and kill any humans who enter. Jerry also gets tangled up in something called a "Full Clear Quest", which turns out to be a mechanism the Star has in place to move the whole game forward: When the Quest is completed, the human, a dungeon god, and an Administrator are called before the Lord Beneath for a Trial. The human decides who dies, and who takes on what role moving forward.
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Somehow Jerry, despite being a small timer and convicted murderer, ends up the first person to actually go through with it, and at the end of the book, along with managing to save Bo, he becomes Administrator Alpha - the first of many, and the Chinese are nipping at his heels to be the second. He establishes a tower under his control, in the real world - but due to politics and people in the American government being dicks, he refuses to bind himself to his country, and his Tower he places offshore of Mexico, over the Chicxulub crater. His partner God is the former administrator, now known as the Slenderman.
Somewhere along the way, Jerry encounters a young woman by the name of Michelle "Chelle" Takoyaki, who was trying to solo-clear the same dungeon that Jerry did, one administered by the to-be Slenderman. Chelle is a Kensei, a Japanese-themed sword class with an attachment to the holy element. Jerry, with methods that are arguably cruel, teaches her how he became strong, and with Merry's help, she rebuilds her holy sword aura into a skill that suits her better, similar to how Jerry rebuilt his telekinesis skill to be more capable.
Merry has likewise been helpful for Jerry all along, helping him better understand his Dungeoneer body and Skills and how they work. It's revealed that Jerry used to be a psychic - but that didn't used to matter, and it didn't seem to matter in the Dungeoneer universe; at least, not until he can overcome some personal trauma of his, embrace the weirdness, and start fucking around with his class with Merry's help. Even so, there are things suggesting that fairies are also spirits, now empowered, and they seem to have a very strange place in the Star's system. They live in the cracks and manipulate fundamentals of the system, but they still unquestionably are a part of that system.
All throughout SFD, there were signs that the real world was teetering on the edge, but trying to make everything seem normal. Dungeon items were taxed on your way out. Portals were guarded by armed national guard troops - with tanks. Criminals lived in the suburbs with stolen military helicopters. Powerful and possibly evil Dungeoneers were organizing around the world. There's soul slavery Dungeon skills that leave people treated like items - and Jerry got one of those skills in his first trip to a dungeon, an act for which he repented, not merely in words, but thoroughly, and he never used that skill on a human, up to the day he broke it. And Jerry's meeting with a Dungeon god was treated, in some ways, like an everyday government meeting. A lot of things seemed to be waiting for events to reach some kind of tipping point, but by the end of the book, nothing had.
And according to Herman, a somehow-terrifying Fairy who serves as an Arbiter for the Dungeons, there's still phases to this game, and things will only get harder soon...

