Microsoft's hotly-anticipated motion-sensing controllers for Xbox 360 videogame consoles made their debut before an invitation-only audience in a Los Angeles theater late Sunday.

Technology developed by Microsoft under the code name Project Natal was re-christened "Kinect."

The potentially revolutionary device uses a 3-D camera and gesture recognition software to let people play videogames using natural body movements instead of hand-held controllers.

It lets people play driving games, for example, by simply moving their hands as if turning a car steering wheel.

On-screen figures in sports or dance titles mimic the body movements of people in the real-world.

No price details were disclosed at the presentation, which provided glimpses at how Kinect lets players control on-screen characters with natural gestures instead of hand-held controllers.

Members of the Cirque Du Soleil entertainment company crafted an elaborate show for the world debut of the new device.

Cirque gymnasts dressed as jungle dwellers cavorted among the audience ahead of the official presentation.

Then a boy dressed as an explorer rode in on the back of a life-size puppet elephant. He was carried to a series of faux boulders, each one higher than the one before.

When the boy reached the crest the top boulder displayed the Xbox 360 logo, and a mock living room with actors playing a family appeared above the audience.

The suspended living room revolved, turning upside down at times as actors playing family or friends walked or played, sometimes standing on walls or the ceiling.

Cirque Du Soleil performers gyrated and twisted below with the sound of tribal drums pounding in the background.

Actors jumped, ran, contorted, swung, and spun as they demonstrated Kinect games that included track, yoga, river rafting, driving, and even fighting as a Star Wars Jedi knight with a virtual light saber.

Video of game play and of actors in action with Kinect appeared on giant screens hanging from the ceiling.

The Kinect world debut was the opening salvo of what analysts expect to be a new battle in an ongoing war between game console makers.

More information about Kinect and game software made for the device will be revealed at a Monday press conference on the eve of the opening of a major Electronic Entertainment Expo (E3) here.

Typically a stage for new blockbuster titles, E3 this year will also be an arena where Sony, Microsoft and Nintendo duel with motion-sensing controls for rival PlayStation 3, Xbox 360, and Wii consoles.

At a game developers conference in San Francisco in March, Sony unveiled a hotly anticipated motion-sensing Move controller that it hopes will fuel new interest in its PlayStation 3 (PS3).

Move wands that synch with Eye cameras on the consoles will hit the market in time for the year-end holiday shopping season, as will Kinect.

Nintendo pioneered motion controls with the launch of hit Wii consoles in 2006.

Sony, Microsoft, and Nintendo are expected to reveal rich line-ups of videogames they hope will win players to their consoles and motion control systems.