Aquilae

I got the hardcover atlas for this yesterday, and it is a fantastic resource. If you want a world all mapped out - and you can fill in the rest - this is the setting to get. A few products dive deeper into the nations, locations, and specifics. But they sell a 'player version' with no landmarks - just cities, and if you want to add all the places of interest yourself - you can do it.

This world can be any rules system, from GURPS Dungeon Fantasy to your favorite OSR to Advanced 5E to Dungeon Crawl Classics. It is a blank slate, all mapped out, and you can do the rest.

I initially used this world for a Pathfinder 1e game, but I am playing Dungeon Crawl Classics now, and the world seamlessly supports that - and all the craziness of a game like that. For any of these points of interest, I could create a crazy DCC adventure out of just the name alone. They would be more realistic places in a more realistic game like GURPS. If i find a set of rules down the road I like, this can be used without too much problem.

I like this world better than legacy settings, such as Forgotten Realms and others, just because of this setting's versatility and DIY nature.