There are many aspects of the Role Playing Game concept that can, in hindsight, be considered revolutionary. While playing the tabletop historical wargames which preceded RPGs, you took on a sort of abstract role that represented the commander or even command structure of an army, and you replayed famous battles from history. With RPGs, you instead take the role of a full-fledged, fictional individual. Previously, those historical wargames had a set of winning conditions as well as a victor and a loser, while current TTRPGs have turned into games with a complex narrative structure, featuring long sessions and even sometimes lifelong campaigns. Back in the old days, games were played one-on-one, or at least team against team. Now, everyone plays alongside each other, usually in large groups, chasing various aims and goals; some team orientated, others covert and personal. And when RPGs were introduced, along with that there was introduced a "Game Master" character who ran everything and described the scenarios like the narrator of a book that the players helped to write.
The GM, or Game Master, was perhaps the most interesting development from those early days. Not only are GMs a repository of knowledge, but they also know what is just around the corner (after all, they are the ones who wrote it). GMs also know and understand everything about the world that the campaign exists in.
It was being a GM that really fascinated me. After all, I was no longer playing in someone else's off-the-shelf world. I was able to, within the confines and logic of the rules, build a world of my own. This one evolutionary step in wargaming had suddenly turned players into gods!
In the early days, there were only a handful of games, and those generally had a limited number of rules. Some games, such as Runequest, came with the outline of a ready-made world for its players to explore and expand on. In Runequest, players lived in such a world called Glorantha, which most of its players still enthusiastically use today. Dungeons & Dragons advocated players creating their own home-brew worlds in which to house their players, though they later released addendums to the rules and also completely new geographical locations to play in which all the necessary detail was provided in modules or campaign settings.
While purchasing an off-the-shelf world is fine if you don't want to do all the work of creating one, I do think that you run the risk of missing a creative opportunity. With the bare minimum of effort, you could create a brand-new world which fits you and your player's styles, and that leans into all of your favorite books and movies and other pop culture. Your new world could be beguiling, interesting, exciting, and most of all... unique.
The original TTRPGs came from fairly cliched places. D&D existed in a world built around a Tolkienesque version of medieval Europe, while the early science fiction games such as Traveler always had a sort of Star Wars feel to them, albeit a grubbier vision which seems to have only been realized through later films. Oddly, for a pastime born out of the imagination, these games were all very conforming.
I did like the early rules for Warhammer Fantasy which seemed to, in some ways, predict the steampunk zeitgeist. But surely it would be better to have a world that mixes and matches all the aspects of games that you find fascinating and flavorsome? Why not have a waterborne, fantasy campaign based on feudal Japan? Or a sci-fi game based on slower-than-light ships based in a local solar system? Why do worlds always have humans as the most common race? What if you had a campaign that contained portals to hundreds of other parallel worlds, each as different and unique as the one world you started on? That has to be more fun than just working your way through the product of someone else's imagination, doesn't it? After all, as the GM - you are a god. Act like it and create!
Do you prefer your own worlds or published settings? Let me know in the comments below!