Twegok

The title is taken from the planet the characters start on...I mean inside of.

The initial setting is known as a Core settlement. A Core settlement is basically a civilization that was realized and evolved inside the hollow core of a planet. Yes, we are throwing out or bending as many physics laws as we can with this one folks. The Cores of Hollow worlds house a predictably bright and molten core that levitates at the center of the Hollow world. Let's say this is achieved via Magic, the source of which is the Molten Core.

Civilization in the Core is very advanced, and technologically inclined, but heavily influenced by the Fantasy genre in this story. So expect high-tech bows and stuff. I haven't thought of antagonists for this arc of the story, but this arc should be as long as half of the Lore series. Very ambitious, but I think we can do it when all is said and done.

Now the Surface is a different story. Only the leaders of the world know what goes on up there, and they are the only ones who know that it exists besides their top operatives. After our characters become Core-renowned and stuff, we get sent up there to support the human settlements that are defending the world from...ALIUMS!

Most flora and fauna of the surface can be described as crystalline, and stay alive by eating...any kind of matter. Normally dirt or absorbing light from the planet's massive, yet far away star(which is very close to death btw, and when it dies, it will generate a super massive black hole). The sunlight on the surface is very faint, and grants the dark gray surface a hint of blue. It more closely resembles moonlight. Magic from the Core does not flow on the surface because of how thick the planet's shell is. Instead, all magic used will come from the Dying Star.

The weapons we acquired from the Core will be useless up there, as only weapons and magic powered by antimatter can destroy stuff. You may be wondering how the characters would survive. Well mages will have immediate access to the most basic anti-magic upon arriving on the surface, so that's how. Although when we can use antimatter, the only things that will be able to threaten the characters will the the various alien races trying to get through the planet's defenses. They will have shields that can absorb a lot of damage from antimatter before going down.

In summary, a Hollowed-out planet is being assault by several crazy-advanced alien races that are thankfully fighting each other as well as the inhabitants of the Surface. This story will feature at least 3 main plot arcs. The Core, The Surface, and then we revisit the Core after everyone finds out there's a Surface world, and that the world is on the brink of destruction from a Super Massive Black Hole. Basically the Core goes crazy because everything they ever knew was a lie and it turns out the government's been doing tons of fucked up shit while everyone was defending against the aliens.

inb4 none of this makes sense and this story will never work.