The advent of Plundr marks "the first time that anybody has built a PC [personal computer] game that's location-based, or uses location data as an element in the game," he said.
What's more, the game isn't limited to the festival grounds. It can track players as they cruise around much of the country.
Plundr uses a program called Loki, which draws on a database of wireless Internet signals across the U.S. to triangulate players' positions.
Most people aren't used to tracking their location this way, let alone using it as the basis for a game, area/code's Slavin says.
"This will get easier over time, as it gets to be a more familiar thing," he said. "This won't be a question in five years."
"With mobile phones, as with computers, play is going to drive demand" for location-based applications, he said.
"If you look at the history of the adoption of new technologies, it's often the case that the drive for adoption is [when the technology is used] for play."
Come Out and Play is one of the first gatherings of mobile social games in the United States, and it features a wide variety of forms.
So-called big games are similar in design to board games but are played across city blocks instead of in living rooms.
Two such games that debuted at the festival, called Crossroads and Capture the Quarter, use players' cell phones to sense their locations.
In both games players run from one intersection to another to capture as many spots as they can and beat their competitors.
Meanwhile, some game developers are using this sophisticated location-based technology to deliver an educational message.
One event at Come Out and Play called You Are Not Here virtually transported people to Baghdad, Iraq (Iraq photos, maps, music, more).
For the festival, the game's creators hung signs around Brooklyn inscribed with phone numbers.
Similar to audio guides in museums, each phone number connected to a unique recording that described a certain site in Baghdad.
(Listen to the You Are Not Here recording for the Baghdad Zoo.)
A double-layered map superimposing Brooklyn on Baghdad showed how the sites in the two cities matched up.
"It's different from reading about it or watching TV," says Mushon Zer Aviv, a student at New York University in Manhattan and one of the designers of You Are Not Here.
"It doesn't take too much effort to imagine yourself transported to this new location."
For example, games designed at the Teacher Education Program at the Massachusetts Institute of Technology (MIT) in Cambridge use GPS and wireless internet (Wi-Fi) signals to track schoolchildren.
The games immerse young players—mostly middle school students—in an "augmented reality" to teach them about science and math.
In one game called Outbreak@MIT, kids play scientific sleuths, trying to track down the cause of a new contagious disease (related photos: tracking the next killer flu).
As they walk through the real world carrying PDAs, the kids meet virtual characters, pick up documents, and find tools that help them solve the mystery.
Location is a crucial part of the game, the developers say, since players could catch the disease if they spend too long near another player who is already infected.
Playing the game helps students learn how to prevent the spread of disease in real life, says Eric Klopfer, an educational technologist at MIT who heads the Teacher Education Program.
The students "start with these ambitious plans of being able to stop the disease entirely," Klopfer said.
But as the students play, they realize, "I want to make sure I stay well, and if I do get sick, I'm going to start transmitting it to other people," Klopfer said.
"So the fact that they are susceptible affects the way they play the game."
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