It's not the great gulfs of distance between people that cause the real problems. It's the tiny differences that really get people riled up. D&D vs. Dogs in the Vineyard doesn't cause nearly the sort of angst and anger as D&D 3.5e vs. 4e.
Which explains why sometimes "Tao of D&D" rubs me the wrong way. He's a simulationist. He's all about building as complete and real a world as he can, and then letting the players run wild through it.
I'm an immersionist. What the heck is the difference? Tao works very hard to have all his ducks in a row from day one. He uses the real world as his template to make the work easier, investigates and designs appropriate weather patterns and economic systems and biologically sound ecosystems.
I, on the other hand, create the illusion via smoke and mirrors. To use a literary allusion, Tao is to alternative history authors like Harry Turtledove and Bruce Sterling, who work very hard to dig into the depths of history to make sure their alternative versions hold together, as I am to Robert Howard and Lovecraft, who create the illusion of complete worlds with a few words and a wave of their hand.
Verisimilitude is vital to both styles of play. Tao achieves it by creating amazing, intricate clockwork worlds where everything hangs together perfectly. I achieve it by allusion and suggestion, and trusting my players will pay no attention to that man behind the curtain, pulling on levers and rattling sheets of metal to create the sound of thunder.
How do you create the illusion? One or two well-placed and unexpected details will usually do the trick. What do I mean by unexpected? Here's a sentence from Lovecraft's “The Dream Quest of Unknown Kadath” that illustrates it perfectly: “In the morning Carter joined a caravan of merchants bound for Dylath-Leen with the spun wool of Ulthar and the cabbages of Ulthar's busy farms. “
Where's the magic? Cabbages. In the middle of this tale of diabolical alien gods, ghouls, and darkly twisted woods, the people of Ulthar grow cabbages. These cabbages have nothing to do with Carter's quest, or with much of anything for that matter. They're a bit of seemingly random local color.
The truth is, the players expect a tavern or inn, and they expect a general store where they can buy more 50' lengths of rope. Even jazzing these up won't really stick in their minds. But they'll remember the way everyone in town has stained their teeth and tongue black chewing on licorice root. The odd way everyone ends any sentence including a personal pronoun by spitting in the dust, or how all magic-users are made to wear purple hats will stick in their minds. These sorts of things don't have to make sense (and, in fact, it helps if they don't sometimes) but they should be small and fairly inconsequential.
The Dream Quest is a great resource for this sort of thing, being a travelogue in miniature, where dozens of tiny places, people, and races are described briefly and then passed over. It's a surreal story, very much a thing of feverdream. It's the tiny details, like Ulthar's cabbages, the yellow silken mask of “that High-Priest Not To Be Described”, the tickling night-gaunts, and the “jasper terraces of Kiran which slope down to the river's edge and bear that temple of loveliness wherein the King of Ilek-Vad comes from his far realm on the twilight sea once a year in a golden palanquin to pray to the god of Oukianos, who sang to him in youth when he dwelt in a cottage by its banks.“
UPDATE: Alexis has posted on his blog with more detail on his technique. Be sure to check it out.
Art credits: James Campbell and David the Younger Teniers