Microsoft's Project Natal demonstrated at E3 last year.

Microsoft will soon begin touting its motion-detecting video-game control system, code-named Project Natal, as a game-changer, literally, for its Xbox 360 console.

But some people inside the Redmond company see Project Natal as a precursor to something much larger. Microsoft researchers have been working on a variety of ways to interact more intuitively with computers -- potentially changing how people use Windows, Office and other Microsoft programs in the long run.

And they’re far from the only ones thinking along these lines. A variety of tech companies have been testing and developing natural user interfaces, as they’re known, and the ones that succeed could have an edge in future generations of technology.

Even Amazon.com CEO Jeff Bezos has gotten in on the act, applying for a patent on a system for making online purchases by nodding, smiling or raising an eyebrow.

All of that broader interest makes Project Natal a key first step for Microsoft -- with more riding on its success or failure than might be obvious on the surface.

The device is a small strip that will be positioned in front of the TV, with an embedded camera and sensors to translate a gamer’s movements into action on screen, and a microphone array to pick up verbal commands. Unveiled a year ago, Natal and related games will be shown next week at the E3 video-game show in Los Angeles, in advance of its release this fall under a final name not yet announced.

Microsoft hasn’t disclosed the price for Natal, which will be sold as an add-on for new and existing Xbox 360 consoles. Michael Pachter, an analyst at Wedbush Morgan Securities, said he expects a price somewhere in the range of $99 to $149.

[Previously: Analysts see Natal adding billions to Microsoft revenue]

Natal follows in the footsteps of Nintendo’s popular Wii, although Natal doesn’t require a handheld controller as the Wii does. Sony is likewise coming out with its own motion-based control system, PlayStation Move, which combines cameras with handheld controllers, in a hybrid of the Microsoft and Nintendo approaches.

But beyond games, Microsoft’s widespread investments put it in a unique position to apply natural user interfaces to other areas of computing. Its researchers envision the technology becoming more immersive and intelligent as it evolves.

“It isn’t just about gaming, but similarly it isn’t just about the camera, either,” said Craig Mundie, Microsoft’s chief research and strategy officer, when asked what Project Natal might signal about the broader future of computing.

Mundie made that comment after his U.S. college tour in November. On that tour he showed natural interface projects including a prototype PC screen that let him manipulate objects on the screen by moving his hands through the air in front of it.

Microsoft has also shown a prototype of a virtual on-screen receptionist that can not only detect when a person approaches but also analyze the situation to predict whether the person is a visitor or employee. And another research project, dubbed “skinput,” uses sensors to detect vibrations in the body -- allowing the user to tap a designated area of the forearm, for example, to control a device.

The company's earlier attempts at alternative interfaces have focused on areas including touch screens, such as the Surface tabletop computer; and digitized pens, such as those used with its initial Tablet PC offerings a decade ago.

Looking ahead, Microsoft's researchers often talk about the potential for a computer to act as an assistant that understand a person’s environmental and situational context and anticipate that person’s needs. The idea, Mundie said, is to combine technologies including machine vision, machine learning, machine hearing, and speech synthesis into new types of intelligent systems. 3D technologies are also expected to play a role.

“It’s the integration of these things that I think is the really big deal,” he said.

Mundie said he sees natural user interfaces augmenting existing input devices, such as the keyboard and mouse, but not replacing them. Company executives have alluded to the possibility of including gesture-based controls and other natural user interfaces in Windows and Office in the future, without offering any timeframe.

Whenever it arrives, the quality of the experience will be key, said analyst Roger Kay, president of Endpoint Technologies Associates consulting firm in Wayland, Mass.

He cited, as an example, Apple’s mastery of the touch screen, making scrolling through a long page on the iPhone or iPad so responsive that it’s like interacting with a real-life object. Microsoft has struggled to replicate that experience in its own touch technologies in Windows and Windows Mobile, he said. It will need to do better if it wants people to adopt and stick with its future natural user interfaces.

“If it’s not that good, people try it as a curiosity and then they abandon it,” Kay said. “People don’t adopt it unless it really works as a substitute.”