Long ago, in a distant star system dominated by a red giant star, the planet Xhuul was devasted by a great struggle between alien god-like beings. The people of Xhuul who worshipped these alien gods were humans who originated on Earth that were transported there by magical gates or by alien creatures that carried them, spanning the great interstellar distances in a short amount of time. Most of the humans were insane cultists of these gods, however a few were not. These were usually prisoners, slaves or sacrificial victims taken to Xhuul. The details of the cataclysm that befell Xhuul, the knowledge of these alien gods, their civilization and technology has been lost, buried and forgotten.
What remains are the descendants of the humans that survived. They live in a few isolated, walled, primitive cities. Each of the cities is ruled by a powerful sorceror, mutant or warrior of great might. These rulers usually have powerful items of magic or technology in their possession that guaranties their position. The people go about their day-to-day lives, usually beneath the notice of such luminaries. However, a few have loftier goals, these are adventurers who seek fame and fortune. Outside the cities there is a large expanse of dangerous wilderness crawling with alien creatures, Cyguggothic emanantions, necrophagic clouds, undead and mutants. There are arid deserts, fetid swamps, fungal forests, montains and badlands. Hidden within this wilderness are ruins of the lost ages of Xhuul. Rumors of treasures, ancient technology and powerful magic await those foolhardy enough to leave the safety of the cities and brave the howling wilderness beyond. There are also things out there best left undisturbed.
The sky of Xhuul during the day is dominated by a red giant star, known as Ygos by the astrologer-scientists of the ruling courts. Xhuul has three moons; Zhlolat, Sartha and Phugo. Zhlolat is a reddish moon, believed to be a desert world. Sartha is green in color, with a heavily clouded atmosphere. It is believed to be covered in steamy jungles. Phugo is black in color. It is believed that the surface is mostly basalt and obsidian. Legends say the souls of the dead travel there. The surface is scarred by giant cracks, most likely great fissures and canyons.