In the latest expansion beyond its main mission of organizing the world's information, Internet search leader Google Inc. hopes to orchestrate more fantasizing on the Web.

The Mountain View-based company unveiled a free service Tuesday in which three-dimensional software enables people to congregate in electronic rooms and other computer-manufactured versions of real life. The service, called "Lively," represents Google's answer to a 5-year-old site, Second Life, where people deploy animated alter egos known as avatars to navigate through virtual reality.

Google thinks Lively will encourage even more people to dive into alternate realities because it isn't tethered to one Web site like Second Life, and it doesn't cost anything to use. After installing a small packet of software, a user can enter Lively from other Web sites, like social networking sites and blogs.

The Lively application already works on Facebook, one of the Web's hottest hangouts, and Google is working on a version suitable for an even larger online social network, News Corp.'s MySpace.

"We know people already spend a lot of time online socializing, so we just want to try to make it more enjoyable," said Niniane Wang, a Google engineering manager who oversaw Lively's creation over the past year.

Although Google is best known for the search engine that generates most of its profits, the company has introduced other services that are widely used without making much, if any, money. Google's peripheral products include its 3-D "Earth" software, Picasa for sharing photos and programs for word processing, calendars and spreadsheets.

Google has no plans to sell advertising in Lively, Wang said.

But the service could still indirectly help the company if it encourages people to remain online longer. Google's management reasons that more frequent Web surfing ultimately will lead to more moneymaking clicks on the ads it shows alongside its search results and millions of other Web sites.

Lively's users will be able to sculpt an avatar that can be male, female or even a different species. An avatar can assume a new identity, change clothes or convey emotions with a few clicks of the mouse.

The service also enables users to create different digital dimensions to roam, from a coffeehouse to an exotic island. The settings can be decorated with a wide variety of furniture, including large-screen televisions that can be set up to play different clips from YouTube.com, Google's video-sharing service.

Lively users can then invite their friends and family into their virtual realities, where they can chat, hug, cry, laugh and interact as if they were characters in a video game.

As a precaution, Google is requiring Lively's users to be at least 13 years old - a constraint that hasn't been enough to prevent young children from running into trouble on other social spots on the Web.

Google spent several months testing Lively among a group of Arizona State University students before opening the service to the public through its "Labs" section - a technology sandbox set up for the company's experimental products.