I know what you mean! I love writing for games. As for scale since I don't have a regular group I was thinking I would do a sort of Colville style West Marches game with a central start point city and then a large scale hex map. Each hex would represent an area with some kind of encounter ranging from a small discovery (item, shrine, person) to massive dungeons that might interlink hexes.
I figure that way I'd be able to have players that don't have to be regular. They could just form a party from the starting city and then explore hexes. I'd reveal hexes as adventurers explored to become "city knowledge".
It also lets me pull fun stuff from every where and adapt it to the game.