Narrative is not a game mechanichttp://www.raphkoster.com/2012/01/20/narrative-is-not-a-game-mechanic/
I urge you to go read this on the blog rather than here, because Google does not let me put all the diagrams in. :)
I love stories. My chief hobby is reading. I was formally trained as a writer, not as a game designer (there wasn’t really any formal training for game design I got started, but that’s another story). I think most game stories are not very good. And I quite enjoy games with narrative threads pulling me through them. When I find a game with a good story, I frequently prefer to the story to the actual game! So please keep that in mind as you read: I love story.
Narrative in a game is not a mechanic. It’s a form of a feedback.
This simple fact is frequently ignored, particularly in games aimed at the mass market.
Let’s start thinking about this by looking at what a game is. Games can and do exist without narrative. The core of a game is a problem to solve. As game grammar tells us, it’s actually typically a series of nested problems: I need to reach this location, which means I need to defeat enemies, which means I need to traverse space, which means I need to mash a button. Some of these, like “defeat enemies,” are complex problems in their own right. Some of them are trivial problems, such as “mash button.”
If you string these together, you’ll typically find that the problems will alternate between abstract problems and simpler interface problems. For example, most turn-based board games alternate between the complex strategy problem of “what move to make next” and the simple interface problem of “pick up piece and move it here.” Board games, of course, tend to be very forgiving regarding interface problems; if you drop the piece, nobody minds if you pick it up and put it where you meant.
....go read on the blog :)