The World is infinite, but venture too far in any one direction and you'll cross into the badlands, deserts of nothingness where life withers and dies, where universal and eventually even mathematical constants begin to break down. The geometry of space at the edges of the World compresses asymptotically as one approaches them. The further you travel in any direction, the thinner reality gets, and the less supportive of life it is. Spirits, demons and other fragments of gods can exist here without trouble.
The wind roars across vast plains of smooth white stone, bounded by unmoving oceans of salt water. There are no trees, no mountains, no clouds. Little for the eye to focus on. This is the World just moments after its creation. The Gods, in one of their myriad debates on the form of the World, declared the Sea and the Land divided by the Coast. As a means to settle the argument on the form this Coast should take, it was decided that it would be essentially random, so no God would have a hand in carving the Land. (Be thankful, the Coast could have been kilometer long letters spelling out names of the more audacious Gods, or worse.)
Standing in the Centre (a sacred place, where magical energy crackles and roils in the air), the Godheart appears directly above, as though it were always midday in high Summer. Toward the edges it gets cooler, and far into the badlands it drops below freezing. Over the year, the Godheart breathes. During Winter, the World stretches slightly, pulling space further from the warmth of the Godheart. During Summer, space contracts, warming the land. At night, the Starlines ripple across the Sky, seeming to stretch to the horizon all around.
The World belongs to no one God.
(Roughly 50,000,000 sq km, or about the landmass of Eurasia.)