The Game Theorist:
Unlike the Gamer, is concerned with whether the game is doing what it is "supposed" to to create the "correct experience". Serves as a check on the Storyteller, keeping them from fudging things in ways that make the other players feel excluded, or introducing Rule of Cool if the game is "supposed" to be serious. Is likely to quote improv terms like "Yes, And" and to maintain that you should "Roll only when there is a disagreement".