Well, now with plenty of time to spend thinking about things, I've come up with a few more ideas for this world, but I am now kind of stuck, mentally, trying to figure out how adventuring would happen, and why.... so let me tell you what I've visualized, and if you all can help me over my "hump", or if I need to discard some ideas and come up with new ones. So:
1) the flat disk of this world has a "volcano" at the center. This volcano creates "dawn" every day when it begins to erupt, pushing light and warmth into the sky. The light radiates out from the center across the sky each day, and then dies away at "dusk", when the eruption ceases. The seasons are controlled by the length of time the eruption lasts each day, which changes on a cyclic basis.
2) the "sky" is an energy barrier of some sort, like a force shield. Within it, there are crystals that look like stars. Sometimes these crystals fall from the sky. They form something similar to a meteor, but when they land they usually cause either an explosion, a wave of magical corruption, or some other dangerous event.
3) On the volcano island at the center of the world lives a VERY powerful being. It is worshipped/feared as a godlike being. It is called the Dragon Queen. there are around a dozen other dragonlike beings of great power and age who claim rulership over the world. Four of them have divided the Ocean (the world is a flat donut, with land surrounding the sea, and the volcano island in the center, and a wall of mountains at the edge) into territories, and 8 more have divided the land into their territories. I'm thinking these dragons feud constantly, warring with each other over who will be the next Mate of the Dragon Queen. Which happens on an irregular basis, every 30-100 years or so. Some sort of event occurs which marks the passing of the previous Mate, and at that point, whichever dragon-ruler is the most powerful leaves his/her realm and goes to the island. In their place, a new young dragon prince/princess emerges to take control of their realm. Which of course prompts all the other dragons to presume that this new one is weaker and less experienced, thus beginning a whole new era of unrest as they all attempt to gain power from the change.
4) religion: there are druids who worship the world. There are those who worship the Dragon Queen, and therefore her Mates, the rulers of the world; these two combined are probably the bulk of the formal religious structure of the world. I think there will also be priests of various elements/forces/states (such as Law or Insight or Justice) but no other "deities" per se. Or maybe there will be many hundreds of "small gods" of things. Every home/city/place might have a spirit. But they would only be "powerful" in their small place. No overarching world deities.
5) races: I'm thinking that humans are limited to 3-4 mid-sized cities (10-50,000 pop maximum) on the coasts, and the lands around them, and are the major seafaring/trading people. There are draconic, lizardfolk, kobolds, elves, dwarves, halflings and gnomes, but VERY few half-elves, because elves actually live on the Feywild and only come to the Prime plane occasionally. There are no orcs, goblins, etc... at all. Just because I always use them a lot... So no half-orcs. However, I may pull in some less-used races for fun. Yak-folk could make good villains. Dwarves live in the mountains on the edge of the world, and actually have tunnels that run from front of one edge to front of the other edge. But they by NO means claim ALL the mountain ring. Gnomes are simply halflings that have adapted to city life; they can and do intermarry. I'll have to rewrite stat bonuses, and come up with some history. I'm generally not a gnome lover and don't see the need for both races in general. Lizardfolk are river and swamp dwellers, somewhat "barbaric" but often involved in river-trade between the coastal humans and the mountain-dwelling dwarves. Halflings are very common - they are farmers and country-folk, living intermingled with humans. I may need another "farmer-folk" people, who live further out in the wilderness and are more hardy. Maybe a centauroid? I want this world to have a flavor of its own, so that could be part of it. Draconic race? I'm sure I want one, but I've never been very happy with what I've seen created, so I may start from scratch on them. They mostly act as soldiers/enforcers for the dragons themselves. Not EVIL, necessarily, unless they work for an evil dragon ruler, but definitely feared/respected by the other races as arms of the great powers.
But what is the History of this world? What do adventurers do? and why? Do they work for the dragons? Exist despite them? What do they plunder? Are there ruins, and if so where do they come from? I'm a bit stumped here...