| Toh'oh Microscope?

History building is the purpose of Microscope the Game.  However, it's really more of a worldbuilding tool or exercise (or activity) when used prior to an RPG.  It's actually sort of like a toy, really.  The only reason, I think, that it's considered an RPG is that when you add a Scene, which is 'below' an Event, you ask a question, choose some characters, and role-play the answer to that question.  So the RPG element is mostly a vignette within the history that might or might not actually have any impact on the history (at least at first glance).

So for example, if the Event is "Oceans fall to reveal previously submerged settlements" someone could choose to add a Scene there.  To begin, the person may pose the question "How did the falling oceans affect the Boogedy Boogedy tribe?"  Then the person rules out certain characters and requires others for the Scene.  This person says no members of the Boogedy Boogedy tribe may be present in this Scene, and TikTok the Medicine Man and Raool the Outsider must be present.  Then each player picks a character (if there are 3 players, and only 2 required characters, then someone needs to create a third character (Raools friend, Gozer) on the spot, or could use a previously defined character, etc.)  Then the Scene creator sets the Scene: "Continuing his vision quest to find meaning in why so many had to die, TikTok approaches a man (Raool), perched on the precipice of an immense drop - a ravine that TikTok does not recall from his previous travels."  Then the players sort of act out, or describe in turn what and how each of the characters in the Scene answer the questions asked.  Maybe it turns out that the ravine is so immense a scar on the land, that the Boogedy Tribe was actually swallowed as the ground split, and the ocean poured into the ravine washing the Boogedy Tribe away.  Raool can confirm this as he was trading with the tribe days before the terrible quake hit.  Gozer has moved into the ravine to see if anyone from the Boogedy tribe remains.

(Wow, again that was long)

Anyway, that little bit of roleplaying makes Microscope a 'game', I guess.  Dungeon World is very much about 'leaving large parts of your map unfinished so the players can create a purpose for visiting'.  Combined with Microscope seems like a fun time.  Throw in some 13th Age connections (that at least has come ties to the crowd-sources world building) and you have the potential for some fun little RPGing!  Or at least a fun background in which to run really dry, uninspired, boring games because the DM is tired from working and raising a family - time will (might) tell!