I just had an idea...
...I just posted it to a Facebook cosplay group to gauge interest.
Have you heard of Ingress? It's a game played in real time where players activate (and create and destroy) trigger points around the world to claim territory for their faction (while removing territory from the opposition).
Who'd be interested in playing a similar real time game over the course of a year or more, covering the entire Sydney metropolitan area. Checkpoints would be activated/created/destroyed by a meetup of real world players in real time, as long as they are wearing their in-character costume. Players could gain status and prestige in the game by confronting each other in pistol duels or shoot-outs between rival posses (using NERF guns), or could go old school and duel with rubber swords [such duels would only count toward the game if they are uploaded for everyone to see].
Except for a few designated meet-ups (which will probably happen at conventions or notified well-and-truly-in-advance), there would be no specific times for games, you play when you want, but you always make sure to post your territory claims in real time. You can duel anyone else who is playing whenever the two of you can organise a time to meet up (in costume). If you work on weekends, no bother, just claim a checkpoint during the week. If you do shiftwork, that doesn't matter either (but it could be tricky to line up a duel with someone who works regular hours).
The general theme of the game is urban fantasy. It's set in the real world, the places of the game are the places of Sydney. There's some magic, some special items to find (and make), rules are pretty simple.
This could end up great, or it could end up terrible.