One thing we haven’t talked much about here is character flags—things about a character that signal what kinds of story elements interest the player. For example, if one of your players has a character with lot of skill in picking locks, then probably you need to throw some locks at that character. This is a major difference between a simulationist take on RPGs and a narrativist one. In simulationist play, the challenges are all laid out in advance, and if you want to excel, you need forethought, scouting, and planning. In a narrativist model, you know what the challenges will be because they’re tailored to your characters, and you should expect that if you’re good at lockpicking, you’ll need to pick a lock.
(Caveat: I’m not a huge fan of GNS, but I find it useful in discussing larger-scale issues such as character flags.)
Obviously, I’m a proponent of looking at character flags to figure out how to structure play. But flags are just the beginning. Russian playright Anton Chekhov has an adage about guns that applies equally to characters in an RPG. That is, the characters created for a game should strongly influence the events of that game.
More specifically, when someone plays a wizard in your game, not only should you let them decipher some runes, or throw in a mystic library to explore, but magic should become a central theme to the plot of the game. Perhaps there are people tampering with the structure of magic, or the old magic is returning, or magic has gone wild and uncontrollable. The point is, the story is about these characters because these are the characters that matter, which we know because these are the characters that were created by the players. They matter because of who they are and what they do.
In Becoming Heroes, we do this mechanically, because each character has an arc and the arc points are specific events that you should expect to see in the game. In Piece of Work, we’re using a system we call Clocks that allows a player a more freeform way to specify what they want to see. But every system has some way for the players to shape the story, if you’re listening for it.