Some time in the 90s, when I first went online looking for info about playing RPGs, I remember joining a listserv called something like world builder’s digest. Or maybe it was just called world building and I had digest mode turned on; I no longer recall.
The advice and work done on that list were mostly top-down, with little attention paid to directly gameable content. The ideal was to work out all the details of your world starting with fundamentals such as geology, cosmology, and history. Then, work your way into the specifics such as economics and ecology, making sure that everything made sense and would stand up to the stray player with a geology PhD.
With hindsight, I no longer think this is a particularly effective way of building settings for tabletop roleplaying games, to put it mildly. But it was a first exposure, and this sort of conversation flowed then more sluggishly online than it does now, and there was considerably less diversity of thought.
A particular creation that made an impression on me from the time I spent reading that list was a setting called Gehennum, designed by one Brett Evill. It was notable to me as a fantasy world that was explicitly designed to buck faux medieval expectations, which even then could sometimes seem bland. (I had no idea at the time that something like Tekumel already existed.) The focal area was an archipelago which drew more from the pacific islands than European mythology and expectations. The body of content Brett wrote about Gehennum also stood out as relatively well-written, especially by the standards of mailing lists about roleplaying games, as filtered through teen memories. In his own words:
In designing Gehennum, I tried to disengage players’ defaults. To do this, I rejected several of most conspicuous standard assumptions, and replaced them with vividly different premises. For example, Gehennum is tropical and oceanic, the Gehennese are not of a European racial type, there are no horses…. I have been different for the sake of being different, which is not in general something I admire. But I have also tried to make Gehennum interesting and good.
For whatever reason, this list and setting came to mind today and I did a few web searches to see if any of that material was still online. Indeed, it looks like Brett still has a site about Gehennum up (copyright mark 1991):
Unfortunately, the link to the map image on that site seems to be dead, but I am glad the work is still online, despite the lapsed time. I was unable to find any listserv archives, but I may just be misremembering the list name.