Recently, I kicked off my first Swords & Wizardry campaign. I wanted dwarves and elves and much of the things that many may consider cliched and trite. But at the same time I didn't want to completely abandon my modern gaming sensibilities.
So, I needed a premise. I wanted an explanation in place for why the world is littered with ruins filled with treasure awaiting the intrepid adventurer. At the same time I didn't want to build a large overarching meta-plot that often becomes an unproductive exercise. Too often I don't actually run the game at hand because I grow weary from the novel-esque preparation. It's back to old school so none of that.
Harkening back to my halcyon days of gaming there was no need for any stinking premise. Anything and everything I could get my hands on became a potential ingredient for the upcoming adventure. Implicitly the world was what it was because I as GM said it was. Or because it was that way in the current module being run. I can't go all the way back to the "style of no style" no matter how much fun it was at the time.
From the perspective of deep campaign prep it took discipline to come up with a mere basis on which reasoning proceeds but I came up with...
Kingdoms of man sprawl across the world. These kingdoms not only define high culture but also great riches. They drive back the dark things that in time become the subject of legend and scary bedtime stories.
Then the world is turning upside down.
The civilizations of man begin to crumble. The things of legend again go bump in the night.
Standing together at the brink, the peoples of the elves and the dwarves each make a promise to the men of the high age whose flame is quickly flickering out.
Then it is dark.
Elves become the machiavellian political masters of the orc tribes in attempt to keep the population of "low" man where he is so that the promise can be fulfilled. The elves believe that the original men will return to once again take their place and that the men who now huddle in round houses and hill forts must be kept where they are.
The dwarves believe that great men will rise above their peers to retake the original high place. The promise compels the dwarves to do what they must to assist the communities of man to make this happen.
Now I have the germ of a game world ready for adventuring.