Manila is a spy game, where the players must compete against the each other using their surveillance, pursuit and covert skills in order to make contact with operatives positioned around the city. Players have specific passwords and specific times to make these contacts, however there are at least two other players with the same information and time slot. Only one of the players can make contact and take away the priceless manila envelope. Once contact is made the player is at risk from the others around him. If caught by them he must hand over the envelope and the information contained within it. Players have a series of contacts to make and time is short, they have to travel fast, make quick decisions and avoid capture.

The contact was waiting on a bench in Covent Garden, surrounded by tourists. I joined a family at a nearby cafe table, scanning for suspicious characters while explaining that I needed to be inconspicuous for the next five minutes. They grinned. On the dot of 4.15pm, I sprinted over to the woman in the mac. "Isn't that an epic church?" I hissed, and she slid a small manila envelope into my hand. Should I sidle away? No, I was already exposed, so I simply pelted towards the next rendezvous. I've spent the weekend playing "pervasive games". When you explain it in the pub, your friends will look deeply unconvinced or froth with bile about devised theatre and geekery. Yet such games have been spreading for a while. And there are all kinds of theories behind them, be they flashmobs, freerunning or games of kick-the-can that encompass a city. Is it a revolution in the way that city dwellers relate? Do they herald the death of the hero in theatrical narrative? Are they some kind of new art form? (The organisers included members of the outstanding Punchdrunk theatre group, who did Faust in Wapping.) Maybe people are just excited about having camera phones?

Nell Boase: The Production Editor for the Guardian Unlimited Arts.