Big Mac wrote:You could be right. The unusual shape of Ginsel, alone, should have an impact on the culture.
And the lack of a moon, and the distance from the sun. We've had a discussion elsewhere about whether or not celestial bodies seem smaller the further away you get in the Spelljammer universe, but I think the general assumption should be that they do. If not, wouldn't every planet in Greyspace seem the size of a moon from Oerth?
(I think the multi-pantheon thing that Forgotten Realms has is a bit of a problem when taken to the sphere level, because you could infer that all the unknown lands on Toril and all the other worlds in Realmspace could have multiple new pantheons).
Greyhawk does that too, though. For example, the Olman and Touv peoples have their own, completely separate pantheons, and before the Twin Cataclysms the Oeridian, Suel, Baklunish, and Flan pantheons were largely or entirely separate. The Baklunish pantheon is mostly separate to this day, although in the Flanaess ethnic groups have blended.
I think some of the gods labeled as "common" might be known on other worlds in Greyspace, but it's reasonable to assume some of the worlds might have their own pantheons as well.
I also think it's likely that even those worlds that have been colonized by humans from Oerth probably had native populations before that, and that native species should still be on those worlds to some extent.
What about the South East area of Hepmonland? I thought that only the North West corner had been developed.

Has Canonfire done a project to fill in the rest of Hepmonland, or would there be space there?
There's a complete map of Hepmonaland in
The Scarlet Brotherhood by Sean K. Reynolds. The northern portion of that island continent is inhabited by Olman and Suel barbarians, some yuan-ti, and some Scarlet Brotherhood influence. The southern part of the continent is mostly Touv. The Olman have a Central American culture, while the Touv are kind of quasi-African, with a unique fantasy pantheon.
Wherever New Koratia is, the people there worship gods of the Flanaess, including Pelor and Nerull (Flan deities), Wee Jas (a Suel deity), Moradin (a dwarf deity), and Pholtus (an Oeridian deity). You'd have to assume that a colony of people (including many dwarves and elves) from the Flanaess, some time after the post-Migrations era mixing of ethnic groups, traveled to the Touv lands, drove away the native Touv and made them stay away, and founded a society more or less like the one they left.
South of Thalos, you have the Tharque Empire, with a few smaller (but still big) islands to the west of the main island. If you think New Koratia would need to be a breakaway kingdom perhaps it might fit over there.
The islands might be a possibility. The WotC page that I linked to above mentioned "rich lands across the Southern Sea" and "war galleys from the South," and you can't get too much further south than that. It might refer to a more southern island, however. If the Southern Sea is the Gulf of Ishtar, the war galleys might have come from the region north of the Barbarian Seameast, which might be wealthier than we generally assume.
Tharquish is supposed to be similar to the Roman Empire in culture, though, and it probably doesn't have the same mix of deities that the Flanaess has. The
Black Moon Chronicles that inspired this part of Oerth posited a monotheistic faith called the Order of Light, as well as a more pagan Black Moon cult, an imprisoned demigoddess called the Oracle, the worshipers of Lucifer, the neutral-aligned Dragon-Knights, Pharoah-worshipers, and the order of the mage-deity Methatron.
Changing New Koratia to Greyhawk or Gradsul would seem to be a waste of a city map.
Assuming you already have a map of Gradsul that you like, yeah. The advantage to making it Gradsul is that the area is already integrated into the Greyhawk setting, and the rich lands across the sea could be the Sea Princes.
But the city is called that, it does beg the question: "Where is the original Koratia?"

According to the page I linked to above:
"The city staggered along through the reigns of eight more kings and ten more barons before being utterly destroyed in the Conflagration of Tael -- an enormous firestorm conjured up by the royal wizard, who felt he'd been cheated by the king. The entire Kingdom of Soes was plunged into a long period of civil war, until one man finally drew the warring noble houses together. Dammeral Ramas, after being crowned King of Koratia, announced his plans to build a new capital.
"A site was chosen some fifteen miles up the River Delnir, where ships from the Southern Sea could still dock, but the surrounding land was unsullied by Tael's magical fires."