Several friends and I got together to create a living campaign setting in Red Markets (10K Lakes [set in Minnesota]), in order to put together a sprawling drop-in, drop-out campaign with rotating GMs. Yesterday, June 28th, the episode on enclave generation in that setting went live over on the podcast I'm part of, Technical Difficulties. We managed to rope in folks from Role Playing Exchange and [insert quest here], so this 'campaign' is going to go live on a lot of different websites...
Any rate, the reason I'm talking about it, besides marketing (which, yes, also doing that), is that I would like to talk about collaborative world building. Don't get me wrong, I think tabletop rpgs already are collaborative world building between the players and the GM over the course of a campaign. But, typically, the GM comes into the campaign with a general sense of the setting in mind. For the 10K Lakes setting however, we needed to build the entire area our characters would reasonably interact with. The system setting material gave us recent history and the general political state of the United States, but we needed to build all of Minnesota, more or less. What exists at all and the interactions between places. I like how it all turned out, so I'm leaving here my advice for others looking to build a campaign setting as an exercise in collaboration.
The first thing, is that everyone involved needs to agree on a general tone. Grimdark and whackety-shmackety-do are not going to co-exist very well and will end of pissing off both sides.
Second, outline a general sense of what you're looking to build. Is it the group's job to build out a single city down to the street names and a map? To only fill in the politics of the area at a generalized, nation-state level with maybe some discussion of geography and topography thrown in? I'm only listing the extremes here, but try to find a happy medium that gives your GM(s) enough to work with and keeps your players' interest during the collaboration phase.
Third, scheduling. Yes, the dreaded owlbear of tabletop rpgs. In this instance though, I have perhaps unusual advice: Let it go. Find the time that the players who are really excited for world building can show up. Let the rest know that they're very welcome, but if they can't come, you're going to go ahead and run the world building because it needs to get done and their ability to play isn't dependent on contributing to world building. OR have folks who can be there bring notes and suggestions from folks who can't. It's world building, you're creating the conditions for plot to happen, not trying to move plot forward.
Fourth, and final, document. Appoint someone the note take for the session and document the awesome stuff y'all come up with. It allows folks who couldn't be there to catch up, makes passing the GM baton between sessions easier, and you don't want to lose all your work, now do you?
Old computer programmer complaint, there, sorry. But really, document your work and comment your code.
And most importantly, have fun.