BRONX breeze tosses her pigtails as she glides down a busy thoroughfare that carries her into the latticework shadows of subway tracks overhead. Dressed in a sleeveless denim jacket and tight flared pants, the young woman draws shouts of obscenities as she weaves between an ill-tempered pimp and a group of barely dressed prostitutes.

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She jumps the curb and turns into a rundown city park after pedaling her dirt bike around a surly homeless man and a tart-tongued street vendor. Racing up a ramp and then vaulting high into the air, she spins in two 360-degree twists before landing in the low grass with a clank, to the cheers of unseen spectators.

It's all in the digital day of a nearly photorealistic trick biker in BMX XXX, a video game from Acclaim Entertainment scheduled for release this month. But don't expect to find any supersonic hedgehogs or heroic Jedi knights lurking in this interactive fare, because this one is strictly not for the kiddies.

BMX XXX is rated M for mature (for players age 17 and older). And from its title to its marketing, the game flaunts its aggressive sexuality, salty language and off-color sight gags.

In an advertising campaign at the game's Web site (bmxxxx.com), Acclaim promises to "Keep It Dirty," using a double-entendre that could just as easily refer to virtual dirt biking as to features like having the computer-generated young woman ride topless or permitting players to follow her to a back alley strip club to watch videos of real women stripping.

Sexuality is the newest supercharged element in a small but significant wave of video games that is soon to reach American store shelves. While the sex play in these games tends to be more suggestive than explicit, what is striking, even startling, is how it has moved from the periphery to center stage.

Advances in technology, particularly the computing power that can now be harnessed to generate realistic animation, is helping to drive the trend. But the shift has even more to do with changing tastes and standards in mass entertainment in an age that is less "American Graffiti" than "American Pie."

"Part of it is marketing," said Vinnie Longobardo, senior vice president for programming at G4, a new cable television network dedicated to video games. "How do you distinguish your game from the pack?''

On the other hand, Mr. Longobardo said, revving up the sexual content in new games might be "a cover-up for not having anything completely innovative and new on the game-play side."

Whatever the game makers' inspiration, or lack of it, some retailers are already making it clear that a line has been crossed. Several have announced that they will not be selling BMX XXX.

Sex, of course, has been seeping into video games for years, from the crudely made hard-core offerings sold online and in adult bookstores to far less explicit permutations like the digital dating rituals in hot tubs in the Sims series. There has long been Lara Croft, the original video vixen with impossible proportions. And in Japan, highly sexual video games have long been popular with both young men and women.

As a result of increases in the number of frames per second, the polygon counts in graphics and sheer processing power, however, characters in computer-animated cartoons are beginning to look and move as real people do - sexy real people. That has disturbed some while delighting others.

Some game developers say that the heightened sexual element of some of the new games is a response to the increasing age of video game players, who are mostly male and less inclined to view video games as children's toys. Their tastes in games simply parallel their tastes in movies, those developers argue.

Consequently, more sexually charged video games will soon be available for play on the most popular game consoles, including Sony's PlayStation 2, Microsoft's Xbox and Nintendo's GameCube.

Aside from BMX XXX, there is Dead or Alive: Xtreme Beach Volleyball, a new installment in a hit game series by Tecmo, a Japanese game developer. The game, due next month, features voluptuous heroines who preen, sun themselves and play high-stakes volleyball in skimpy bathing suits on a tropical island.

"The eye candy in the game characters looks beautiful," said Tony Tarpey, a marketing manager for Tecmo. "Dead or Alive has always been known for sexy characters."

Last month Rockstar Games, the maker of the Grand Theft Auto series, released Grand Theft Auto: Vice City, which surpasses a hit predecessor not only in the extent of its violence but also in the abundance of sexually heated situations, bulging bust lines and megabytes of digitized poolside sirens.

Though it has yet to reach consumers, BMX XXX, by far more the most risqué of the new games, has generated so much criticism that Wal-Mart, Circuit City, Toys "R" Us, KB Toys and Best Buy have banned it from their shelves.

Sony had second thoughts about releasing the game uncut for its PlayStation 2, the most popular game console. Alan B. Lewis, the spokesman for Acclaim, said that after discussions with Sony, the game's developers removed a function that allows players to design a female biker to appear topless. In addition, a BMX logo now obscures the breasts of the real-life strippers who appear when a player wins a bonus.

So far the game remains unchanged for the Xbox and the GameCube. Spokesmen for Microsoft and Nintendo said that those companies had not asked for any changes in BMX XXX. When asked about the game, John O'Rourke, Microsoft's director of worldwide Xbox marketing, took the opportunity to note that Xbox is the only console with parental controls and could be set to lock out all M-rated games.

Acclaim executives are hoping that the editing of the PlayStation 2 version might allay the concerns of retailers who have refused to stock the game. "The company believes that the PS2 version may be more palatable to those retailers,'' Mr. Lewis said.

But editing and parental lockouts seem unlikely to satisfy the game's opponents, who assert that the game is fundamentally unacceptable.

The American Family Association, a group that says it advocates traditional values, became so incensed recently upon learning that Best Buy was considering selling BMX XXX, which the association denounces as a pornographic game, that it mobilized its members. Best Buy received more than 33,000 e-mail protests about the game in a single day last month, the association said.

"Our contention is that these games promote negative social behavior," said Randy Sharp, director of special projects for the association. "They teach boys to disrespect females."

Executives at Acclaim, based in Glen Cove, N.Y., maintain that critics of the game are applying a double standard.

They emphasize that the video game industry is maturing, with more than half its players now over the age of 17. At the same time, they say, the realism resulting from advances in hardware and design blurs the line between video games and movies, which routinely include nudity, raw language and adult situations.

"We are disappointed that there are groups who fail to see how this humorous product is truly on par with such widely accepted mainstream entertainment experiences, including movies like 'American Pie' and TV shows like 'The Sopranos' and 'Sex and the City,' " Greg Fischbach, co-chairman and chief executive of Acclaim, said in a prepared statement.

In an interview, Ben Fischbach, Acclaim's senior brand manager and director of Internet properties, said that the decision to up the ante on BMX XXX was simply an attempt to give an older game audience the kind of entertainment it wanted.

Game industry analysts say that M-rated games - usually so rated because of graphic violence - are now the fastest-growing genre in the home market.

Over the last two years Acclaim has released Dave Mirra BMX and Dave Mirra BMX 2, games based on a star rider in BMX, or bicycle motocross. Together the games have sold three million copies. But when it came time for another sequel, Mr. Lewis said, the company wanted something fresh and daring.

"The direction that we were taking with BMX XXX was to design a game from the ground up for a mature audience," he said. "They're not always wanting a guy on a bike on a ramp. They're not always looking for games that are warm and fuzzy, that are cute. They want stuff that's relevant to them and their lifestyle."

The core of the game remains true to its BMX legacy, he said, although the name Dave Mirra was removed by mutual agreement.

Mr. Lewis said that Acclaim expected BMX XXX to sell well despite the controversy surrounding it.

"When we were designing this game," he said, "we anticipated that certain mass market merchants would not carry the title, but other merchants might carry more."

He added, "Consumer demand is not going to diminish.''