I just deleted the first 90% of this essay, which was a long essay on why community is important. Let's just pick up from "community is important" and...
The big-city non-community we've created is largely due to the sheer size of our communities. When you see the same people every day, you'll probably get to know them okay. But when you go downtown, there are thousands of people milling around, and they're different every day, every hour, every minute. They're all either going somewhere or doing something, and you can't really get to know them even if you want to.
With that said, let's assume augmented reality. Actually, let's assume brutally limited augmented reality. Let's assume that our augmented reality consists only of audio from our iPhone (or other 3G device). No video, no added devices, just sound, either to a headset or not.
Everyone playing this little game builds a sound for themselves - not a specific song, but a basic progression and instrument. When they are near to another person playing the game, that person's phone synthesizes their progression into a song, combining it with any other virtual sounds nearby. The strength and prevalence of the progression is based on your proximity to them. So if you're inside, and people playing the game are walking around on the street, the song you hear has haunting little "improv" bits with their progressions. If you're sitting next to people, you hear their sounds combining into a coherent song.
So picture this. You're sitting on the bus, and you hear a beautiful song. You're still quite big-city American, so you look around a bit to try to figure out who it could possibly be, but you don't approach anyone. You big coward.
The next day, you hear the song again.
And the next.
That person isn't unaware of you, either: they are hearing your song. Day after day.
You hear the song walking down the street... it's obviously that girl over there with the jacket, you've seen her on the bus every time. What do you do?
Sheesh, it's giving you every opportunity to connect to someone. You'd have to be an idiot not to talk to them.
Moreover, as you get used to hearing people's songs, you'll start to get an idea of who people are the instant you hear their song. If someone's got a Mozart-like sound, they are a very different kind of person from someone with a Beastie Boys sound. You can also get the feeling as to who it is by triangulating and playing "hot/cold" like when you were a kid. It's probably that guy looking around for you.
Standing in line at the coffee shop, you hear a new song. Smile and wave, maybe push some buttons to change your song around a bit, do a little interactive songwriting...
This is possible with the utter lowest grade of augmented reality. This technology is available right now, and affordable to the majority of people living in big cities. In fact, many of them already have a compatible device.
Could be interesting, don't you think?