Frontloaded vs Backloaded settings
There is, in my opinion, a mild schism (among the major schisms) in the OSR regarding setting construction: Greyhawk and Blackmoor get shat upon for being “vanilla D&D” or “generic” while a revolving cast of flavor-of-the-month settings that describe themselves as “weird” or “gonzo” are held up as masterpieces. I care not for your reviews of published settings but rather wish to extrapolate on my own meditations.
First, “frontloaded settings” must be defined, as their existence is dualistic with backloaded settings. These are settings that are strange and outre from the very outset, possibly even from character creation or even the introduction: McKinney’s Carcosa, noisms’ Yoon-Suin, or Gibbons’ Bx Mars are what I consider to be good examples of such types of settings. The worlds are alien; cultures are weird; demi-humans are either replaced or deleted; science, pseudo-science, and science fiction cast a shadow over them. They are testaments to creative genii, yet their own alien novelty forms a barrier to play: Of what use dungeon delves and GP when most of Carcosa languishes at a neolithic level? What of crab-man’s inhumanity to man? What if I don’t want to play someone who’s naked all the time?
The solution is pretty obvious: “Just change it.” Or rather “(you, the referee, can) just change it.” Which is true, but this puts all the burden on the referee AND undermines the whole reason for using a published setting in the first place (so the referee doesn’t have to do the hard work).
Now, there are “backloaded settings”, sometimes called “generic” settings: The ones with the kings and knights and castles and orcs and dragons and not-quite-medieval civilizations. This is where Gygax’s Greyhawk and Arneson’s Blackmoor started. But they didn’t end there: They changed, they EVOLVED based on player decisions (some of those players even being the creators themselves!). Those historical timelines have some referee-created trivia but the important parts are all because of player actions.
But even then, Blackmoor and Greyhawk weren’t as vanilla as claimed, there were aliens and magic apocalypses and weird shit. To go full D&Dcore, turning everything into the same diluted and flavorless melange, is something you can do with WOTC D&D or a host of other alleged competitors, and should be avoided. The balance is between the two, I think, vanilla enough to facilitate immediate player engagement but with sufficient indelible weirdness from the referee’s own mind to add excitement. But above all, the referee must be willing to allow the EVOLUTION of his setting based on player actions.
Player Agency vs Setting Integrity
The previous point rolls into this one. I recall many years ago, WOTC had a regular online advice column called Jedi Counseling for their Star Wars RPG (at the time, the Revised edition, which was also technically my first RPG), written by one Sarli. A flustered GM laid out the situation: The game was set at roughly the same time as A New Hope (0 BBY or Space Year 1977) and his party had decided to punch in the coordinates for Yavin IV (the big Rebel base in the climax) for unspecified reasons. Sarli’s solution was to have them wind up at the fake Rebel base named early in the film or arrive at the actual base after the Death Star had been blown up and the Rebels fled. Why did this GM even need to ask what to do? Why did Sarli reply with that? Because if the party got there and killed Luke or seduced Leia or jumped in X-Wing and blown up the Death Star or awakened Sith ghosts (press F for the pre-Disney EU) then they wouldn’t be playing a Star Wars game anymore, they’d be playing a Star Wars AU fanfic game because the setting changed irreversibly (if/until time travel became canon). It’s the tightrope you walk with established settings, especially those derived from media: The group wants to play in the setting but if changes are allowed then, sooner or later, they will no longer being playing in the setting.
But I believe this problem extends beyond published settings into homebrew settings. This is, I think, the root of the old “you shouldn’t stat gods because the PCs will kill them” mindset, not some true ideological take on the nature of divinity but a pre-emptive petulance about the players not appreciating the hard work that the GM making these (unnecessarily) complex characters.
Player agency, the ability for the players to freely act, goes hand-in-hand with consequences. Yes, the party can jump to Yavin IV and TRY murk Luke, but how will they cope with both the Rebels and Papa Vader seeking vengeance? They can storm Olympus and TRY kill every god in the place while stealing all the loot, but how do they deal with the things the Olympians were keeping under control? Give the players a rope and see if they tangle (or hang) themselves . . . or someone else.