Many worldbuilding maps, even those for fantasy RPGs, are modeled off parts of or the entirety of the real world. There are ideas to take different directions. There are other ideas to go for instead, as Edgar Grunewald of the YouTube channel Artifexian posted a video some years ago about ideas for creating original world maps. Alien biosphere projects like Alien Biospheres by Biblaridion and Life Around a Red Dwarf Star by Project Rose involve the people behind them having ideas for the shape(s) of the starting continent(s) and ideas for the drift patterns of the landmasses over millions of years. Sometimes, worldbuilders for tabletop RPGs have come up with maps completely original, and with accuracy regarding land masses, river shapes, where terrains are located, and so forth. If you thought of ideas for multiple naturalistic conlangs and the cultures that would speak them, you might need this information to know the type of world such people and languages would exist in. J.R.R. Tolkien did that when he created the precursors to the Elvish and other languages, then the world to put them and their hypothetical speakers in that would be the setting of the Lord of the Rings books.
And there's also the people that might inhabit it. Most D&D worlds are inhabited by humans, elves, dwarves, and various other entities. The merfolk of D&D are different in form from the merfolk in the images by Syfyman2XXX. So for a crossover RP with those mentioned continuities and franchises last chapter... IDK what to do. Also, I might need to speak with Alex and others about ideas they might have. Will need to include context though.
Anyway, there are ways and reasons for conlangs to exist, and goals to set down, though examples exist to demonstrate where people need to be careful.
If creating a tabletop RPG, it might be best to include multiple conlangs. I mean, "Old and/or Middle English", "Elvish", and other familiar fantasy languages are common throughout several D&D campaigns, even the campaign in Dungeons, Dragons, and Dames. I mean, the LotR books do it. So do the Dune books(maybe). Other worldbuilding projects also practice this multi-lingual inclusion.
Biblaridion's conworld now includes Oqolaawak, which is similar to Native American, Polynesian, and East Asian languages.
Nekāchti, which is similar to Latin.
Edun, which might be like Germanic languages(including English), though less fusional.
Ilothwii, which is like the Eskaleut family of languages.
Two conlangs are in the process of being revised, though Biblaridion has other projects to get done. Anyway, I plan on, when he gets around to writing his story and when I recruit attorneys, adapting his story into a series, and I have ideas for unique options of cast members. They'll need to learn Biblaridion's conlangs though. Anyway, he fleshed out some aspects of his conworld.
And he would eventually reveal an important piece of the conworld.
Anyway, for my RPG conworld for that crossover RP, I'm thinking of overlapping the map of the Refugium with a map of what the world was thought to have looked like during the periods of Old English or Middle English.
I'm not a flat-earther, though if I was making it flat in ways similar yet different from the Refugium, I might need some trial and error, even when taking advice from Edgar.
When the map is created, I'd need to figure out which animals should inhabit the custom world, even compared to many D&D worlds. And where to locate the speakers of the protolangs.
