Tokyo, Japan (CNN) -- The game begins with a teenage girl on a subway platform. She notices you are looking at her and asks, "Can I help you with something?"

That is when you, the player, can choose your method of assault.

With the click of your mouse, you can grope her and lift her skirt. Then you can follow her aboard the train, assaulting her sister and her mother.

As you continue to play, "friends" join in and in a series of graphic, interactive scenes, you can corner the women, rape them again and again.

The game allows you to even impregnate a girl and urge her to have an abortion. The reason behind your assault, explains the game, is that the teenage girl has accused you of molesting her on the train. The motive is revenge.

When does a video game go too far?

It is little wonder that the game, titled RapeLay, sparked international outrage from women's groups. Taina Bien-Aime helped yank the game off store shelves worldwide.

"This was a game that had absolutely no place on the market," said Taina Bien-Aime of women's rights organization Equality Now which has campaigned for the game to be taken off the shelves.

But the controversy that led to stopping sales of the game instead took it viral.

That was how Lucy Kibble and Jim Gardner in Britain heard about it.

"I think the idea that you can do it by wholesale banning is just never going to work anyway because we downloaded it for free off the Internet," Gardner said.

In the case of RapeLay, he was right. It is still readily available on dozens of Web sites, sometimes for free.

What happened to RapeLay is an example, said Bien-Aime, of why Japan needs to police game makers.

"It's obviously very difficult to curtail activity on the Internet. But the governments do have a role in trying to regulate this sort of extreme pornography of children, both in their countries, and through the Internet ," she said, adding that they were calling for the Japanese government "to ban all games that promote and simulate sexual violence, sexual torture, stalking and rape against women and girls. And there are plenty of games like that. "

Those games are known as "hentai games." Almost all feature girlish-looking characters. Some of the games are violent -- depicting rape, torture and bondage in detail.

Step into a game shop in Akihabara, Japan's electronics district, and hentai games are readily available. In minutes, we found a game similar to RapeLay. The object here is also revenge: Find and rape the woman who fired the player from his imaginary job. Along the way, the player can rape a number of other girls and women.

Hentai games are not new to Japan. This country has long produced products the rest of the world would call pornographic. But before the arrival of the Internet, such items stayed in Japan. Now, once a game goes on sale in Tokyo, it is digitized and shared everywhere.

Japan does have censorship laws for sexual content. In games and videos, genitalia are obscured, even if it is animated. But Japan's laws do not restrict the themes and ideas of the games.

A national law that would make possession of real and virtual images of child porn illegal is under discussion, but no serious legislation has moved forward in Japan's parliament.

CNN contacted the Gender Equality Promotion Division in the Gender Equality Bureau of Japan's Cabinet Office, which is charged with handling the hentai gaming issue.

Despite repeated calls over a period of weeks, no representative from the government office would comment to CNN on camera. The office refused to make a statement on paper. A spokeswoman would only say over the telephone that the Japanese government was aware that the games were a problem and it was checking to see if self-policing by the gaming industry was enough.

A member of the Institute of Contents Culture, who did not want to give CNN his name, said restricting game themes limits freedom of expression.

"In my opinion, RapeLay's storyline went too far. However, if a game creator wants to express something and create content out of it, a government or public entity shouldn't have the power to restrain it."

Lucy Kibble and Jim Gardner, the gamers in Britain, said trying to control games on the Internet was futile and that content control was up to parents.

"The idea of banning it, or telling people what they can and can't do just because on the off chance some kid might get involved with it is just ridiculous," said Gardner.