I ran a first session of Diaspora today; it was entirely comprised of setting- and character generation, which went well - so far, the system looks interesting, and I can't wait to get it started and see how it works in practice.
What struck me while playing is that it's important for lots of questions to be asked during the game. That sounds like a banal observation, but it isn't: I'm not talking about the necessary sort of questions that players have to ask ("Where is the exit?" "What are the orcs carrying?" etc.) but questions which spur the questionee to think, and thereby create.
For instance, I was describing one of the worlds, in one of the systems we were creating, as being a water world, populated by Melnibonean-esque decadent epicureans. One of the players cut in, "Do they live on the surface in big floating cities, or under the water, or what?" And I was forced to think, "Well, where do they live?" And in answering the question more detail was added to the setting: creation by question in action.
There is a lot of power in this, and it applies not just during shared setting-creation type games like Diaspora: it applies in any kind of game - I'm reminded of a Yoon-Suin session I ran online in which one of the players asked whether hijras existed, and I had to think, "Well, do they?" The answer was yes, and another detail was added to the world. But it just as frequently happens during character generation too: "My character is about six feet, built like a brick-shit house, and he's carrying a glaive." "What does the glaive look like?" "Well....It's engraved with runic patterns." "What do they mean?" "Er...he doesn't know, it's a family heirloom and it's a mystery." And so on: questions have power.
I think this comes from the fact that, like using random generators, questions spur creativity through restricting the options. It is the same adage that I've used before: give a man a paper and pencil and say "write a story" and he'll take 10 times as long to come up with something than he would if you'd said "write a story about a murder", and it'll probably be 10 times less interesting. Likewise, saying to somebody "Come up with a world" is a thoroughly different proposition to saying to him: "What is the geography of your world like? Is there a desert? What kind of people live there? Are they warlike? Do they do drugs?" By restricting his creativity, you give it legs.