The bikini-clad coed draws a blank on the first question: "Which king in a deck of cards has no mustache?"

Clueless, she adjusts her skimpy top and says, "Spades?"

"Wrong!" shouts the game host, comedian Matt Sadler.

Knowing what's coming next, the college guys grunt and hoot and the babes scream "wooo!" For missing the question, the happy coed must pull her top down.

Topless babes are the payoff in "The Guy Game," a new trivia video game whose raunchy banter and racy content falls somewhere between barely decent and indecently bare.

To win, players must answer trivia questions correctly and guess whether busty coeds will. The more right answers, the less the digital "knocker blockers" obscure the nudity. By the end, it's topless rope jumping and sack races.

Get ready for video games gone wild this fall: Several mainstream game publishers are releasing bawdy games containing nudity and explicit sexual content. "The Guy Game" and "Leisure Suit Larry: Magna Cum Laude" are already out. An adults-only "Singles: Flirt Up Your Life" is being sold online, with a toned-down M-rated version on the way. November will bring "Playboy: The Mansion" and "Rumble Roses," the first all-women's-wrestling game, featuring unquestionably dirty moves.

These are the raciest games ever made for the mainstream market, their graphic graphics setting a precedent for a whole new sexual dimension. Some experts say it's the next evolution in the industry, one that -- combining the two hottest forms of entertainment today, video games and sex -- could expand the focus of the "M" rating from bad language and violence to prurience.

Why now? Because the first gaming generation has grown up. The $7 billion-a-year video game industry now caters to players whose average age is 29, not the nerdy teen stereotype, according to the Entertainment Software Association. Yet 85 percent of all games sold in 2003 were rated "E" for everyone or "T" for teen.

"It would be naive to think, given that market," says ESA President Douglas Lowenstein, "that forevermore video gaming would be a completely pure and chaste field."

Leading the pack since its August release is "The Guy Game," which one reviewer called " 'You Don't Know Jack' with boobs," referring to the popular trivia video game series. Jeff Spangenberg, CEO of TopHeavy Studios, makers of "The Guy Game," says reviews have been mixed and message boards and blogs have been buzzing.

"Some people see the game for what it is, which is a game geared toward guys about things guys like -- competing against your buddies, showing up your buddies and topless nudity," he says. "But other people were just so offended that there is sex in a video game and they could not get over that."

Spangenberg founded TopHeavy Studios two years ago to focus on innovative game ideas and "The Guy Game" is its first release. He says the game stands out for showing video nudity rather than animation. "It's a new concept," he says, "and I'm sure when the movie industry first had topless nudity, a lot of people couldn't believe it."

He wouldn't provide figures but says the game is selling well.

Enough to foretell a trend? Heck, this season even "Pro Fishing Challenge" lets you customize your angler into a perky chick wearing a skimpy two-piece, and "Outlaw Golf 2" hits the links loaded with sexual innuendo, lewd characters and peekaboo pixels.

Konami's "Rumble Roses" was inspired by the Miller Lite beer TV ad last year in which two scantily clad women wrestled in a fountain. Contestants strip down to tiny bikini tops and thongs. In the mud-wrestling mode, their skimpy attire at times appears to disappear. Says product manager Rob Goff: "With Rumble Rose, sure there are great visuals and really sexy models, but at the core of it is a great game."

If the topic is naked, you can bet Playboy isn't far from the action. Coming to a video-game store near you is "Playboy: The Mansion" -- a chance for players to be Hugh Hefner and build the Playboy empire. An M-rated takeoff on the popular company-building game "Tycoon," the game's hardly all business: Around practically every corner is a bevy of bunnies. The game play is digitally animated, but success unlocks a bonus archive of photos of actual Playmates.

"This is not a game so you can see dirty pictures -- you can use the Internet for that," says Joe Minton, president of "Playboy: The Mansion" publisher Cyberlore Studios, whose other titles include "Risk: Global Domination" and the futuristic MechWarrior series. "It's a really cool game. It's like seeing an R-rated movie that's a really good movie." (And, sure, you buy Playboy to read the articles.)

The game, along with several other sexual-content titles, got a publicity goose from October's Playboy magazine: Video gaming's most come-hither vixens were featured in a five-page nude pictorial called "Gaming Grows Up." Pinups for the PlayStation population -- "an attempt to say the gaming market is maturing," says Playboy senior editor Scott Alexander.

Among those showing off their digital assets is "Leisure Suit Larry's" Luba Licious, a hottie he's after, and BloodRayne, the half-vampire half-vamp of the action series of the same name.

"She's coy and there is definite innuendo, but there's no rampant sex or nudity in the game and I don't anticipate her ever getting naked there," says Ken Gold, vice president of marketing at Majesco, maker of "BloodRayne 2," released Oct. 12.

Sex in video games isn't altogether new. Game designers made a few adult titles before ESRB ratings began labeling content in 1994. The original late-'80s "Leisure Suit Larry" was a floppy disk of campy shenanigans in which disco loser Larry tries to seduce overly endowed women. The cartoony sex-scene graphics were cheesy, the humor doofy. And it developed a following.

Since then, bikini-clad babes and slutty prostitutes have popped up in various games. But last year's "BMX XXX" took the cheesecake, rewarding players for completing bike stunts with video clips of topless strippers.

Many stores wouldn't stock it. Its maker, Acclaim, filed for bankruptcy in August -- though "BMX XXX" didn't single-handedly bring it down. But if reviewers dismissed its nudity as gratuitous, this year's games are getting a more serious look.

Last month Eidos, maker of the Tomb Raider series, released the adult-only "Singles: Flirt Up Your Life" online. Simply, it's like the popular life-simulation game "The Sims" but with full-frontal nudity (both genders) and no-sheets sex.

But Eidos's producer, Tom Marx, says it's much more than that, calling the game a 3-D relationship simulator that goes as far as the player's relationship skills take it. "You actually have to work at it and build up the relationship with a complete stranger and eventually you may get lucky," says Marx, adding that the game targets 18-and-older players, men and women.

And not just men and women together, he adds. "If you want to bring two ladies together or two guys, knock yourself out, you can do that. . . . 'Singles' should cross many lines, men, women, gay, straight and everything in between."

Probably none of the new games qualifies as pornography, but most would garner an "R" rating in the movies -- even the animated games like "Leisure Suit Larry: Magna Cum Laude," released Oct. 5. Now Larry's chasing college coeds.

"It's simply a very irreverent, almost sophomoric game," says Phil O'Neil, president of Vivendi Universal Games North America, a video-game giant whose titles range from kid stuff such as the Crash Bandicoot series to the sci-fi action-adventure "Chronicles of Riddick: Escape From Butcher Bay."

This is the company's first venture into sexual content, and O'Neil seems reserved at grouping "Leisure Suit Larry" among the new racy games, comparing it instead to the films "American Pie" and "Scary Movie."

"We thought this would resonate with today's gaming audience," he says. "Now we have guys who were 'x' age 10 years ago who think this stuff is pretty funny."

But Vivendi Universal passed on the opportunity to publish "The Guy Game." O'Neil says "it was a little more gratuitous and provocative than we were interested in doing."

Explicit content can make for marketing headaches, including getting approval from the three big console makers -- Sony, Microsoft and Nintendo -- who have final say on which disks spin on their systems.

Majesco's Gold says many publishers are hesitant to make sexual-content titles because they would have a limited distribution base beyond video-game stores and the Internet. "You know it is not getting into Wal-Mart and Target," he says.

And some critics fear that video gaming's naked ambition will take Pong to porn. "Video-game makers move into the pornography realm because there is money to be made," says Ann Simonton, co-founder of Media Watch, a national nonprofit women's organization that has lobbied against violence and sexism in video games.

"The characters in 'Leisure Suit Larry,' they look extraordinarily young with the gigantic breasts -- kind of an ideal fantasy of the 12-year-old," she says. "This has enormous impact on a culture where we can't seem to teach sex education along with the joy of emotional connection and intimacy. It's all about looking at girls as objects."

Patti Miller, director of the Children's Media Program at Children Now, an advocacy group, is concerned about the effects on girls' self image and boys' attitudes toward females.

"This sends a troubling message about the role of girls and women in their lives," she says, "that young women and girls are valued for how they look, their bodies often portrayed as sexual objects."

But game maker Steven Manschot says sexual content tends to attract attention disproportional to its impact.

"I don't think sexual content is gaining ground. From a global standpoint there is still a large taboo," says Manschot, the Netherlands-based creator of LoveChess, a downloadable game whose richly endowed graphics and eye-opening animations turn the traditional intellectual game on its head. When these chess pieces, naked Greek and Trojan gods and goddesses, jump each other, they jump each other sexually.

Concerned parents rummaging through their teenagers' video game piles can breathe easy, says ESA's Lowenstein.

"There are close to 1,000 games for a console and PC that come out every year and you are still looking at a very, very small number that are probing this area," he says, adding that M ratings and descriptions, along with parental guidance, can keep sexual-content games out of the wrong hands.

"I don't think there is any question there are some games that are pushing the envelope when it comes to sexual content," he says. "But it remains to be seen how successful those games will be. In the end, it is still all about the quality of the game."

"The Guy Game," left, stands out for showing video nudity rather than animation. The dweeby Leisure Suit Larry, above, is back, this time in hot pursuit of coeds."Singles: Flirt Up Your Life" features frontal nudity.In "Rumble Roses," the wrestlers are scantily clad women.Not to be outdone by "Singles: Flirt Up Your Life" (above and below), Playboy is jumping into the adult video gaming fray with "Playboy: The Mansion," left. The game gives players a chance to be Hugh Hefner and build the Playboy empire. The M-rated game is not all business, as beautiful bunnies appear around every corner. A bonus archive of photos of actual Playmates is a reward for successful play. The $7 billion-a-year video game industry serves players whose average age is 29. "Singles: Flirt Up Your Life" is just one of a burgeoning number of adult-oriented video games being sold online.