ATLANTA — There's no alien world behind the virtual reality gear, just a modestly decorated living room that can be seen without the video goggles.

But once the game "AR Facade" starts, you might wish there were space invaders. That's because it puts you in the middle of an excruciatingly uncomfortable argument between Trip and Grace, a bickering thirty-something married couple.

Do you play moderator and decide to help broker a truce? Do you instigate them by complimenting Grace on her decorating style or pretending to be impressed with your pal Trip's place? Or do you act as if everything's peachy while their arguing heats up?

Whatever path is taken, this participatory soap opera at a Georgia Tech research lab is at times funny, awkward and intriguing. And it's always intense and emotionally draining.

"AR Facade" is an "augmented reality" game, a genre that mixes a virtual world with physical reality. The technology is still emerging, though someday people may play such games with gear as simple as their cell phones.

So far, scientists seem to be having fun with the possibilities.

At the University of South Australia, researchers created a version of "Quake," the popular shoot 'em up game, where users with a wraparound visor and a backpack walk around streets and fight superimposed computer objects that only they can see. A human "Pac-Man" game, created at the University of Singapore, places virtual yellow dots along the city streets and allows players to become the game's hero or one of the Ghosts set on catching the little gobbler.

Some have a more practical use, too.

Mark Billinghurst's "Magic Book" is an animated children's book that turns into a 3-D pop-up, changing with each page when viewed through head-mounted goggles. The New Zealand scientist also is helping develop "AR Tennis," which lets gamers use their cell phones as rackets on a virtual court superimposed on a real table. The action is watched on the phones' screens.

"Within five years people will be able to easily experience Augmented Reality applications on their mobile phones, in their homes, schools, hospitals, workplace and cars," he said. "One of the most exciting things is that the current generation of mobile phones have the processing power, display resolution and camera quality necessary to provide compelling AR experiences."

Billy Pidgeon, a games analyst at the research company IDC, says the field shows promise, especially if its future is staked to the growing computing power of cell phones and other handheld devices.