//mightymushroom's description (part 1?)//
Though the shape(s) of the land might be drawn (as for a map) on the inner surface of sphere surrounding a single sun, the land itself is hardly so smooth. It rests in many-layered Tiers, the height or depth of each and consequent nearness to the central sun contributing greatly to the local climate. The Tiers themselves are relatively flat — or rather, gently curved to the theoretical sphere they cover — with small hills at most. About half are covered by oceans of water, acting as sources and sinks to support a hydrological cycle. Curiously, it is not only the lowest Tiers that are pelagic in nature, thanks to the extraordinary (perhaps magic-like) phenomenon of the Walls between Tiers.
Tiers are separated by stony Walls that stretch near-vertically between a Tier and its neighbors, often many leagues in height/breadth/extent. In places, too, there are great chasms and crevasses, where the Walls of nearby Tiers plunge far beneath the landmasses themselves. (In only one spot is there a mountain range where the Walls rise upward from two adjacent Tiers, and not particularly tall at that; for the most part the Walls replace mountainous terrains from an outer-skin world with their passes and sheer rock walls.) Where gravity (or rather its analogue shaped for an inverted surface) works as expected upon the Tiers with a consistent pull to the ground, its effect may seem warped and strange upon the Walls: binding objects tightly to their sides in one place and hardly at all in another. There are even places where streams and rivers of water may appear to run uphill from the perspective of the flatter plains on either side, and upon the largest Wall, connecting the second-highest of Tiers with the third-lowest, rests an entire Sideways Sea that foams and fountains in the scarce 'gravity' near one end. Thus the journey from one Tier to another may be easy or difficult according to local conditions; no doubt life will adapt accordingly.
Night is provided by a large gemstone bowl that shades the earth from the central sun without completely blocking its light. The aptly-named Nightshade is primarily built of deep blue sapphire streaked by lighter aquamarine. It is studded irregularly with stones of many colors, including garnet, citrine, peridot, and more. These gems are the equivalent of stars and constellations. They appear scarcely near the bowl's center and more and more densely near its edge, until the rim itself is ablaze with refractions of splendiferous color for the periods of sunrise and sunset. The Nightshade is somewhat smaller than a half sphere. It is also slightly tilted with respect to its axis of rotation (Or is that the world rotates while the bowl is still? Who can say?), such that the "north" pole of the world shines with perpetual day while the "south" pole is constantly bathed in auroral twilight.
The White World Whale Möbius Dictus is tutelary spirit of the central sun who takes the form of a vast, silvery-white cachalot to mortal sight and his back is said to be the size of at least a Tier. He swims upon the brilliant waves of the sun itself. From this vantage point, He is said to be the watchful eye of the gods Who sees all and offers His testimony whether each mortal soul, once its body has passed away, ought to be admitted to the paradisiacal World-Within-the-World at the center of the sun, or returned again to the mortal Tiers, or cast into the uncaring depths below the crevasses. He is followed by a cloud of attendants in the form of ghostly albatrosses, who individually may fly out of the sun to bring fortune or ill luck, plague or health to individuals and households. The albatrosses are sometimes scatterbrained or silly, designs of the Mercury spirit; and though they may be commanded by any of the higher powers as well as Möbius Dictus Himself, they are not to be relied upon for anything important.
//and that's enough for one entry. I'm interested to see what other ideas might occur, as well as more detailed flora and fauna. Who lives in the depths, the heights?//