Well I have a setting I've been working on, off and on, for a few years now, just worldbuilding with no particular expectation of playing a game in it. It's nowhere near enough to actually do anything with though because I'm a perfectionist and yet also scatterbrained.
Anyway, it's called Pantellia. A tidally locked planet - that is, one side of the planet always faces the sun, the other always away. It's several Earth masses and has a huge atmosphere and loads of water, so it handles the temperature difference well - extreme winds blow between the day and night poles all the time, keeping both of them at livable temperatures. In the middle, around the "equator", there's loads of coastline and perpetual, eternal rain from numerous storms blowing in off the ocean, and that region, called "Drisque" (drisk) is where most stuff takes place.
There are no humans on Pantellia, but there are humanlike beings called demaren who have horns, four arms, and digitigrade feet. There's also "dragons", and frog-people / naiads, and spider people, and there used to be cephalopod-like people a million years ago who founded an extremely high-tech civilization that covered the planet, but they all died out in a world biotech war, which incidentally resulted in massively speeding up the mutation rates of life for a while, hence all the other sapient species.
Oh, and there's the Mabelen, the sapient fungi, the relics of the Ancients (those ceph beings) who uploaded themselves into the global fungus-computer internet before the apocalypse. But over the million years since they have grown godlike, incomprehensible, and quite probably insane. They also are the only beings that still fully understand biotech, and all "magic" - really biotech done via engineered fungal spores - is a gift from them. "Mages" are people of other races who have fused with the fungi that produce these spores and can control them. I'd go on - there's much more - but this is getting too long. :)