It's a game. No, it's an ad. No, it's advergame.

The online games that were embedded in ads sponsored by the Internet travel agent Orbitz are coming back, this time on a Web site of their own.

The Web site (orbitzgames.com), scheduled to go live Wednesday, revives games that have proved popular since they began appearing inside Orbitz online ads in 2001. Fans of the frivolous may once again use their PCs to play "Sink the Putt" and "Swing for the Fences," as well as try new ones such as "Island Hop."

The games and Web site, created by an agency in Chicago named 15 Letters, are the centerpieces of a promotional campaign for Orbitz offering free travel prizes. The budget is estimated in the low seven figures.

The Web site includes elements of the mainstream advertising campaign for Orbitz like a cameo role for the game show host Wink Martindale, who appears in commercials for Orbitz created by the Chicago office of Young & Rubicam, part of the Young & Rubicam Brands division of the WPP Group. Visitors to the orbitzgames.com site will be able to send "Wink-o-gram" e-mail messages.

The comeback of the Orbitz games is indicative of a trend known as advergaming, in which marketers offer games online that double as ads--or vice versa, depending on your perspective--to capitalize on the growing interest among computer users in so-called casual gaming, playing short games whether brain teasers or time fillers.

The goal of advergaming is to encourage consumers to engage in a branded experience--that is, spend time voluntarily with an ad. That is usually more efficient and effective for a marketer than to chase after consumers with ads they are likely to shun. Among the other brands that have added sponsored online games to their marketing tactics are Jeep and Life Savers.

One "huge risk" in advergaming is that sponsors may "become better known for the games" than for their products or services, said Henry Harteveldt, an analyst who is the vice president for travel research at Forrester Research. Orbitz provided Harteveldt an advance look at the Web site so that he could discuss it with a reporter.

Advergaming that is done well "strikes a good balance between being creative and different," Harteveldt said, "and making sure people know who's behind it." He praised Orbitz for making "the brand part of the URL," or Web address. By contrast, some advertisers offer games under names like the Life Savers Web site, called candystand.com.

Orbitz executives have been mulling for some time ways to give computer users regular access to its online games. They first appeared in the form of what are called pop-under ads, that is, banner ads that turn up on a computer screen after a Web site is visited. Many computer users consider such ads annoying and have installed blockers that screen out pop-unders and their counterparts, pop-up ads.

Still, "when people find out you work at Orbitz, they want to talk to you about the games," said Mitch Truwit, chief executive of Orbitz in Chicago, part of the Cendant Corporation, "and they call us up to ask where they can find 'Sink the Putt.'"

Research by Orbitz shows that computer users spend an average of 3.5 minutes playing each game, Truwit said, and in the last year they have sent more than 1.8 million "tell a friend" e-mail messages recommending the games to others.

"One out of two people who buy travel online say they also play games online," he added, "and one out of three say they're familiar with the Orbitz games."

The idea to devote a Web site to advergaming came from Randy Wagner, who joined Orbitz in May as chief marketing officer after working on global marketing at McDonald's.

"My nephew in college said he spent 20 minutes looking for 'Sink

the Putt,'" Wagner said, "a game he was going to play for three minutes." Research into the Web site included "sending some of my brand team to a law firm in Chicago," she added, whose employees had organized intramural Sink the Putt tournaments.

"Why would a company dedicated to travel have a game site?" Wagner asked rhetorically. "Because travel today is a game and we want people to know Orbitz is the way to win that game."

Harteveldt said he also liked the Orbitz decision to mix in travel-themed games with more generic sports-oriented ones. The travel-related titles include Run for Your Flight and Pick Your Path.

Staff members of 15 Letters have been working on the Orbitz game ads since their debut, when they worked for another interactive agency in Chicago, Otherwise.

"People say they hate pop-under or pop-up ads," said Mark Rattin, president and creative director at 15 Letters. "Our challenge was figuring out how to make people love them."

After what he described as "a lot of experimentation," the first game ad went up, called "Pluck the Chicken." Pulling out the feathers yielded a golden egg, and a click on the egg took computer users to Orbitz.com.

That had "three times the interaction" of pop-under ads without games, Rattin recalled, so the advergaming began in earnest. The golf game remains the most popular, he added.

Ideas for new games come from many sources, Rattin said, describing one's genesis: "We were in a meeting here talking about the concept of Orbitz making it easier to find the travel you want. Someone said, 'As easy as shooting fish in a barrel' "--the inspiration for a new game, "Fish in a Barrel."

Research shows that online game-playing is becoming as popular with women as it is with men, Rattin said, which is important because Orbitz seeks to appeal to both sexes. "Women tend to play more puzzle-oriented games," he added, while men generally prefer "shoot-'em-ups."

Wagner said she already picked her screen name on the Web site, during its test phase: "Brand Goddess."