The thing about Mage: The Awakening is that it has a canonical in-universe faction, the Free Council, that's theoretically trying to do what Harry is doing in MoR. Unfortunately, since the authors of the game aren't rationalists, this activity is only portrayed as an opaque black box.
I've been enjoying reading Less Wrong fanfiction, and I wanted to suggest another fandom that should have at least one rationalist fanfiction: Mage: The Awakening. It's a roleplaying game about "modern sorcery." My description can't really do it justice...