You may not yet know it, but gamers will soon be quitting their living rooms and heading outdoors.
Handheld consoles and laptops made gaming portable, while the Nintendo Wii made gaming active. Now active, portable gaming is possible thanks to GPS and improved graphics becoming standard in cellphones.
By 2013, the world's largest handset manufacturer, Nokia, expects half of its phones to be GPS capable, giving them the ability to fix their locations on the planet to within a few metres.
Apple's iPhone, seen as a benchmark for other manufacturers, also has GPS and many handsets have motion-sensing accelerometers, just like a Wii controller. Games studios are racing to exploit a new world of what is called "pervasive gaming", where everyone carries a powerful gaming machine in their pocket.
The first wave of games are largely based on treasure hunts, with a phone guiding users through a set of waypoints to a particular goal.
UK firm LocoMatrix does it using photos of a neighbourhood. An onscreen thermometer lets a player know if they are "getting warmer" as they close in on the next waypoint, and users can create and share their own treasure hunts.
Richard Vahrman of LocoMatrix was inspired while using handheld GPS for walking routes, and says location-aware gaming could have health benefits. "If we could make a compelling game on a mobile, then youngsters might get out more," he says.
Other treasure hunt games include GPS Mission, from Orbster in Karlsruhe, Germany. But games that blend real and virtual worlds can offer a richer gaming experience.
Another example, Stamp the Mole, starts with users defining an arena using GPS, before chasing moles visible only on their mobile screens inside it.
The Shroud, from Florida firm Your World Games mixes the real world around a player into the world of an adventure game. Travelling to real-world locations can unlock or solve quests in the virtual world.
While some location-aware games can be played anywhere, others may be strongly connected to a particular area, says Constance Fleuriot of the Pervasive Media Studio in Bristol, UK, those strongly connected to a particular area, say, Manhattan, and those that can be played anywhere.
"The former could be linked to the history of an area and give you a different viewpoint of a place," says Fleuriot. "The latter are portable."
Phones with GPS also allow players to discover each other's locations and meet physically as well as virtually. That kind of camaraderie will appeal to many, says Mark Eyles, principal lecturer in the Advanced Games Research Group at the University of Portsmouth, UK.
"If they are designed correctly, they will attract people who currently aren't gamers simply because they are social and fun," says Eyles.
Just as the sometimes madcap physicality of Wii gaming has loosened inhibitions, Fleuriot says social location-based gaming can do the same.
"We had a group of adults who played an activity game of Stamp the Mole outdoors and they said: 'We look like prats, but at least we're all prats together,'" says Fleuriot.
Jon Dovey, a new media expert at Bristol University, says GPS gaming is likely to be the first application to introduce the masses to being connected digitally to their surroundings, something he calls "ambient connectivity".
The 14-to-19 age group will lead the way, Dovey says, because their social lives depend heavily on cellphones.
"As soon as you get the link between texting, social networking and GPS-enabled devices, you are going to get something that takes off like wildfire among young people because their culture is already primed for it,
But being able to discover the physical location of other people has downsides. Researchers at Portsmouth University have had to abandon GPS games projects because they cannot get approval from the ethics committee.
"Already there are social networking applications for the GPS iPhone which let you see where other iPhone users are," says Andy Bain, lecturer at Portsmouth University's School of Creative Technologies. "If I were a thief I'd abuse that knowledge right away to get myself more iPhones."
Commercial games developers are not subject to the same ethical scrutiny as academics, he adds. It could be left to their customers to work out how to avoid anti-social gamers.
In fact, truly mobile gamers must learn to weigh up a range of new hazards. Bain worries that gamers may focus so hard on their mobile phone's small screen that they lose awareness of real-life hazards, such as traffic on a busy road.
The developers of The Shroud have clearly thought of this already; its terms and conditions state baldly that "You will be responsible if you or anyone else is injured or killed while you are playing". Game over.