SJ:
It seems likely that once s/he tires of on-wiki games (which is admittedly difficiult, considering what an adrenaline rush our new gaming platform is), with a positive view of the local community, this will be a natural outlet for other notes and work...
Mh-hm. Notes and work, eh?
Here's the opposite scenario. We're all fun-loving people and we allow this guy to set up his "Wikigames" project as an unofficial part of Wikipedia. He starts about 20 new game pages, all as subpages of Wikipedia:Wikigames, which we accept as legitimate. He invites some of his friends to join. A #wikigames IRC channel is set up. A parallel community grows in that section of Wikipedia of people who primarily play games.
While every single human being on the planet should read Wikipedia, I'm not convinced that every single human being on the planet should edit it. There are people who are mentally ill, utterly ignorant, fundamentally irrational, belligerent, rude, paranoid, malicious, and worse. We can edit their pages, but we have limited access to their brains. There are people who, in spite of our best efforts, will never become useful contributors to the site. I like to believe that their number is small. The cynic in me says otherwise.
The fact that Wikipedia is an encyclopedia acts as a social filter. If you encourage and allow the growth of a parallel community, that social filter loses much of its effectiveness. Moreover, even the process of post-discovery discouragement may no longer work, because these users have their Wikigames ghetto to return to and come back from, where rules like NPOV are as relevant as Schopenhauer is to the Furry fandom.
I therefore strongly oppose the growth of parallel communities. Wikigames need to be very limited, and linked to the encyclopedic nature of Wikipedia itself.
Erik