This morning, out of the blue, it hit me that I can summarize my approach to GMing tabletop RPGs in a single, concise principle: There is no curtain.
The curtain is, of course, a reference to The Wizard of Oz — in which a curtain conceals what the titular Wizard is actually up to in his chamber. When his deception is laid bare, Dorothy and her companions see the Wizard, his power, and his machinations in an entirely different light.
That accurs’d drape
So what does “There is no curtain” actually mean?
It means that when I GM, I don’t hide what I’m doing from the other players. That means no fudging die rolls, of course, and no literal curtain-analog in the form of a GM screen, but it’s bigger than that. I’m upfront about not doing any session prep beyond thinking about the game and perhaps looking over my notes from the last session. Likewise, if something is decided on the spur of the moment — my favorite way to make decisions as a GM, because I want there to be a roughly equal distribution of surprise around the table — I don’t try to conceal that.
“There is no curtain” is shorthand, encompassing a lot of what’s in my lengthy, comprehensive 2016 Yore post “Alchemy, agency, and surprises.” Play is what happens at the table, not what I’ve plotted out in advance behind my curtain; that in turn means that what makes the game fun is player agency, and the attendant consequences thereof. It also emphasizes that we’re all players, I’m just a player who (probably, depending on the game) has a few different responsibilities — and not, say, an all-powerful wizard who knows all and sees all…or at least deceives the other players into thinking that.
“Deceive” is kind of a strong word in this context, isn’t it? There’s nothing inherently wrong with “playing behind a curtain” — it’s just not a GMing style that interests me in any way. (Though if a group isn’t on the same page about how the game is being played, that can lead to serious problems.) But it’s the correct word for me, because of the Czege Principle: “when one person is the author of both the character’s adversity and its resolution, play isn’t fun.” The curtain is a metaphor for the deception required to pretend that it’s interesting when the GM is in charge of challenges and their resolution.
This has nothing to do with, say, hiding the dungeon map from the other players, or keeping monster stat blocks to yourself during play, or even running a prepared module — provided you don’t force the other players to stick to it, or bend the game to ensure that the module works as written. There’s no deception there; everyone at the table wants that dungeon to be full of surprises. But if, say, I’m planning to use a randomly generated dungeon during a session, I’d share that — because I don’t want it to be a secret. The randomness is a feature, not a bug.
What’s interesting is what comes next, and that’s up to the other players. And, as a massive added benefit, when everyone at the table has the same set of expectations about how the game is going to work, all of the players — GM included — can much more easily support each other in making it fun for everyone. If there’s a curtain then that responsibility falls largely to the GM, and I can’t abide that model of play.
I learned this from you, tremulus
Lots of stuff in my gaming past has contributed to my current perspective, but one of the biggest influences on this principle was tremulus.
tremulus is PbtA Call of Cthulhu, more or less, and right up front that premise begs a question: How can you play a satisfying mystery when the GM doesn’t plot out the mystery in advance for the other players to solve? The answer is twofold.
Firstly, instead of plotting out the mystery, the GM comes up with some story threads and how they might resolve themselves if the PCs never showed up. And secondly, everyone at the table knows the mystery isn’t prewritten. There are mechanics enabling players to contribute elements to the mystery; there are moves that ensure that core bits of the unfolding game don’t exist until the moment they unfold. There’s no curtain in tremulus, and seeing that in action was a powerful experience for me.
So there it is: There is no curtain. I enjoy thinking about, and coming up with, GMing principles — and I hope this one has some utility for other gamers, too.
 Set the time machine to 2008: this post from the salad days of Gnome Stew collects seven of my maxims for GMs. The aphorism in this vein that I’m most proud of, though, comes from even earlier — 2006, when I was writing Treasure Tables: Being a GM is like using a 150-watt bulb.