This happened a while ago. So one of my mates decided to run a game of Mage: The Ascension for two other friends without actually properly reading the book or learning the system first. (I wasn't there.) They're into the game for a bit and one of the players has his character do something dangerous. And the GM goes: "Ok...roll for...DANGER!".
I think it's brilliant. He understood, instinctively, from being a gamer, from the dramatic tension of the moment, from playing other games, that this was a moment that needed something. That the fictional tension had to be appeased somehow. In roleplaying games that something is almost always a die roll. So he called for a roll.
But he didn't know the system all that well and he didn't know what he should ask the player to roll. So what are you rolling? Well, what is your character doing? He's doing something dangerous. Roll danger.
I'm interpreting it my own way but it appeals to me immensely. This very basic, fiction-first, instinctual insight into the dynamic between table (players, dice, boxes) and imagination (clouds, fiction, shared imagined space). It happened spontaneously, but for me it hit the absolutely right note of game design.
Design that is directly tied to actual play. Where you design from what is really happening with these people at the table, and writing it down, because it works.
Design where you roll because there's actually something happening in the fiction. I'm rolling. What are you rolling for?
Design where you roll because the fiction couldn't bear it being otherwise. Where you pick up the dice because it follows from the fiction that you simply must.
Design where (because of all the above) the roll matters. Because we stake something on it and you can't drop the dice on the table without something happening.
I could go on a tangent why that story happened with a Storyteller System game, but I'd be ranting.