Greatspace

Greatspace is a solar system with seven planets and an asteroid belt. It has an interplanetary Spelljamming civilization made up primarily of humans and elves, with significant populations of dwarves and halflings., Three of the planets have significant populations:

Thesalys: the original home of the humans in the system, and the ruling planet. 5 nobles houses rule 5 major areas, of which House Shambrath has been the dominant for centuries. Thesalys has one moon, Myle, which is largely uninhabited except for a one community, which is the dominant military base and trading port in the system, Port Shurius.
Lagor’s World (or Lagor, for short): colonized by the humans several centuries ago. Densely populated, with many different cultures spread across a large number of independent countries and city-states.
Hecht: beautiful, mountainous forest planet, sparsely populated by humans and elves. Original home of the elves in the system, colonized by humans a few centuries ago.

Up until a couple of years ago, Greatspace was a peaceful, prosperous system that kept largely to itself. There was very limited contact with other systems, including the core triad of the “Known Spheres”: Realmspace, Krynnspace and Greyspace. That peace was shattered when a vampire named T’Laan, disguising himself as a bard, ingratiated himself at the court of King Gorath Shambrath, with ill intent. Over the course of a few short years, T’Laan charmed the King and became the power behind the throne. When the heir apparent, Prince Bruin Shambrath, tried to expose him, the controlled King declared him an outlaw. Bruin was forced to flee the system, and eventually found allies in Realmspace in the form of a group of adventurers who would come to be known as the Knights of the Reluctant Circle. Once his control was complete, T’Laan set his plans in motion, which included darkening the sun of Greatspace, building fleets to serve the plans of his Drow and Illthid allies and to carry people off to set up colonies of human livestock in T’Laan’s home system, Darkspace. A year or so of T’Laan’s rule, and the darkening of the sun, was enough to collapse the economy, set off wars for resources between neighbors, and generally throw the sphere into chaos. Eventually, the Knights of the Reluctant Circle were able to defeat T’Laan’s allies on Hecht (where the drow had set up a secret base, bolstered by bionoids

Geography

From innermost planet out:

Karrington: lifeless, burning wasteland
Skora: poisonous methane atmosphere, no known life
Thesalys: ruling planet, varied cultures. 5 Houses rule 5 major areas, of which House Shambrath has been the dominant for centuries.
Lagor’s World: densely populated, with many different cultures.
Longpoint: uninhabited due to violent seismic and volcanic activity.
Asteroid Belt: covers ~85% of orbital arc.
Hecht: beautiful, mountainous forest planet, sparsely populated by humans and elves
Boran: frozen, icy planet, mostly uninhabited.