The 500 Kingdoms- Genre-Savvy Fairy Tales Game?

[Weirdlet]

Hey, all. I was having a thought a moment ago, and I'd love to get some brainstorming going. In Mercedes Lackey's The 500 Kingdoms books, fate is shaped by something called the Tradition, a magical force that pushes people down the paths of well-worn stories, with Godmothers as the network of magicians that try to ensure happy endings and prevent all-too-easy tragedies from unfolding. A certain amount of genre-savvy is a necessary trait in a wise ruler, and protagonists can deliberately invoke certain tales by their actions in order to gain Traditional support for their goals.

I can't help but think this could make for a fun game, depending on the group. Has anything like this been done before? What system, or tweaks to an existing system, might be appropriate to playing this sort of thing out?

[Sith_Happens]

The Talecrafting mechanic in Changeling: The Lost is basically exactly that.