You have all lived on the world of Mondial – the Celestial Tower – your whole lives, although you may not know the specifics of how the world works or why you're here. There's a general mood of fatalism in this world. Most people are born, live their lives, and die on the floor they're born, and the majority never even see the bottomside or topside floors at all. However, the legends of this world are full of heroes who marched up topside – Godseekers climbing the tower to find the domain of of the New Gods, whoever they are, or Deathseekers, descending the tower to investigate or, in some feverish fancy, to either slay or worship the Hole at the Bottom of the World that will one day swallow the whole world.
	You have likely grown up in one of the many “Civilized” floors dotted up and down the tower, which is usually a packed-in melting pot of many species trying desperately to co-exist with the constant fear of the Nether outside leaking in and killing them all, or turning them into mindless nethertouched beasts.
	That is your shared knowledge of this world you live on. It's not a planet, per se. It's more of a structure – impossibly huge and reaching up and up towards the domain of the gods, and down to the hole. Each floor is a cross-section of a different world, built up by mythical immortals living atop the tower, building up to outrun the constant destruction wrought by the hole down below.
	There is little enmity between you and other races, with a few exceptions. Dragonborn, Tiefling, Gnomes, and Dwarves in particular are “agitated” races. They tend not to stay in one place and are encountered most often as adventureres. Dragonborn have an instinctive wish to climb, Tiefling are simply unwelcome due to their nethertouch, Gnomes are weirdos who view Mondial as a lush paradise, and Dwarves chase the dreams of their long lost civilization. Humans, Elves, Orcs, Halflings, and most other races are “settled” races, in that they tend to stay in one place... but not always. Anyone can join the ranks of the Godseekers or Deathseekers, for any number of reasons. Eventually everyone will have to climb the tower if they live long enough for the bottom of the tower to fall down into the hole.
	Magic is a force of nature. Nobody knows what it is, exactly, but it exists, it can be studied, and you can learn to control it. Divine power is borrowed from the New Gods – possibly without them actually knowing you're worshiping them. Creatures and celestial/otherworldly beings are trapped on Mondial same as everyone else, and offer their power to warlocks. Music and Bardic tradition is one of the basic things keeping culture alive and together in the face of the Nether.
	What is the nether, though? Nobody knows exactly what it is. It flows like pitch molasses, and is a deep, dark violet color. The radiation can cause unexpected effects – magical mutations, mysterious sickness, the births of Tieflings – and direct contact can cause the weak to die immediately, and cause the strong to transform into a horrible beast, or at least come away somehow... changed. Gravity becomes strange around the nether. The Hole at the Bottom of the World is said to be made of pure nether. It could also be a creature that produces the nether. Nobody knows.