Worldstree is a GURPS campaign world of High Fantasy
in the vein of Legend and The Dark Crystal.
The theme is of Mythic Fantasy, a place of Legends and Heroes, or Great
Wars and Looming Dooms. And no Humans. And no out-of-context
Worldstree is not the name of a planet. Worldstree is the infinitely? tall tree at the center of a disk approximately 8,000 miles across (incidentally the diameter of the Earth). The disk is ringed by a border of mountains, the Ringwall Mountains, that extend into airless space. The Mountains are widely believed uncrossable and the Underside is a subject of Myth. The Sun seems to follow a seasonably variable ellipse around the disk, but Worldstree Astrology is complex subject, at best. It should be obvious that Magic, not physics, is the underlying rationale of Worldstree.
The actual name of the world varies from people to people, of course, but it can be said that few are aware of the idea of "world" as a unity. The Faeries usually refer to it as a garden or a valley, the Celenes call it "Home", for what it's worth. "Worldstree" will serve as a common name, though it may refer to the Tree itself or the world entire.
One of the defining characteristic of this Myth is its Animistic Nature. Everything and everybeing encountered is assumed to be intelligent, from the Celestial Bodies to the unassuming Fauna. Worldstree is inhabited primarily by the Immortal Races of Myth, from Elves to Dragons, and there is a near infinite variety of playable Races and terrible Monsters
Worldstree exists in Mythic Time. Most of the Races live between memorable
Moments, and define the passing of Time by them. For the truely Immortal,
the Seasons and Years are pointless to count. This also is part of the
Nature of this Myth - there is always Something Big happening, because
those are the only times that Matter.