Growing a game world

The original game assumed that you invent and create your own dungeon and campaign world. Gygax said so, in the white box, in the article in the Europa Fanzine that described Greyhawk Castle dungeons, and in the 1e DMG on page 86ff. He actually gave very good, practical advise how to invest your effort economically, if you wanted to do this. He did not believe people would buy adventure modules, as you could make up your own. So, in the beginning, there were no commercial settings and not enough published adventures to be bought*. 

Creating your own adventures, dungeons, and campaign world from scratch is massively time-consuming. You need personalities, factions, organizations, gods, cities, castles, dungeons, monsters, history, legends and adventures. Few people have the time to do this. 

Thankfully these days, you have no need to. There are many colorful campaign books just waiting for you to be picked up. The Forgotten Realms is a setting described in rich detail. Just buy what you like, and maybe tweak it to make it fit your own game. Improvise, reskin, and incorporate published adventures shamelessly.

The point of this post is that I recommend you embed all your adventures in the same world. The publishers make this easy now with all the official modules set in the Forgotten Realms. But even if you pick up a generic adventure, or an adventure originally set in Greyhawk or Glorantha, or whatever other world, place it there, maybe reskinning some of the names or monsters.

If  you do this, over time the campaign world becomes familiar to you. Stories and heroes in the world are created by the players adventuring in it. You know the towns and who lives there. You can have the retired player characters make cameo appearances. You can have NPCs tell yarns about their deeds of daring. It feels much more like a real place, where things happened. Because they did.

Gygax' home campaign created the world of Greyhawk. Mordenkainen, Drawmij, Myrlynd, Bigby, Robilar, Tenser, Otto, and all the other famous D&D characters originally were player characters or henchmen (the Wizard's tend to be better known, as they have spells named after them). 

If you use published materials, you obviously also do not own the rights to them, and will not be able to publish your game world. I know that I never would be able to publish mine, as it is based on the Darlene Map, and populated by adventures from Monte Cook, Dungeon magazine and classical TSR, next to some I wrote myself. And there is no need to have these rights. Your world will be dear only to you and your players, because you know it, and it is full of memories.

* We had a similar situation in Germany. There originally only were four published modules for Das Schwarze Auge, all for starting levels. Later the publisher had a hard time to keep up with teenagers that had endless time on their hands and were hungry to play. So I started on writing my own adventures, and learned that it can be a lot of fun and a great outlet for your creativity.