I've quoted Larry Niven before, specifically with regard to his commentary on collaborative world building, and more specifically, the introduction to his short story "Flare Time" in the N-Space compendium (page 342 for those of you playing at home,) where he says you must have a dictator among the group in order to really get anything done.

As the duly appointed dictator of FPL continuity, I managed over 20,000 words on the subject before I realized the Khazan I was building was not the Khazan people wanted. I've never been plagued by a dearth of ideas, and I could easily fill in every minute detail myself, but then it isn't a shared world anymore and we're all just playing in Ivan's sandbox. I already invented a highly suspect form of social government, balkanized the Soviet metahuman contingent, and built a self-aware computer with a fondness for Welsh Corgies. What else do you people want from me?

So we're back to ground zero, with the caveat that several people's half-baked ideas are serving as cornerstones for a continuity that nobody really wants. Khazan is on Earth, to make things "more realistic" but a supervillain takes over an entire continent and writers insist the world won't sit up and take notice because that continent is full of brown people. A very small group of people have conceived a library's worth of storyline already, but none of them have a reliable track record of ever completing anything ever.

There are other noteworthy concerns in crafting the environs for a shared experience, including several places where the world we inhabit doesn't live up to it's potential. Jerry Holkins has been forthcoming with the following bit of hilarity:

Like other atheists, I can see some of the rookie mistakes in the "world building" God has done, by which I mean Jehovah, with his cryptozoological fascinations, underutilized themes, flat protagonists, and the prevalence of barbarism - but my own work is rife with genuine concerns. When I have my way, I gin up a world where life is a doomed accident, a planet whose crust is nothing more than a prison for an inconceivable evil, while a floating city of half-angels wages a genetic pogrom to scour mortality from their race. If anything, I've managed to create a scenario where leprosy actually sounds pretty good.

Of course I've come across the opposite problem, not wanting to stifle creativity, I've possibly made things too easy for Khazanians and their ilk, although any system in place to maintain the Superheroic status quo necessarily tips Khazan's needle toward "Top 10." The problem is, in spite of my insistence that superpowers are by no means ubiquitous, the creator itself requires the expenditure of Ability Points, meaning one has to be both willful and creative if one wants to craft an ordinary person.

What does all this mean?

What happened "the last time" was that Khazan ended up being defined by its presence in stories. SLJ Plaza, the core, the Fallen Tower, the LotMU Subway... landmarks, characters, and backstory show up in random fics and sorta become folded into the fabric by default. Then, later, people complain about lack of continuity but too bad because it already exists. Essentially, anyone who had the wherewithall to finish a story got to create the world.

So here is a recitation of something I said a year ago:

Write something NOW, and it'll more than likely become continuity. Procrastinate, and you'll have to work around what other people have already written.