On 16th September, the Electronic Software Ratings Board for video and computer games will turn 20 years old.
The board was created as a response to parental 'outrage' against violent video games such as Mortal Kombat . It is thought to be modelled on the success of the Motion Picture Association of America's ratings system.
Like the MPAA, the ESRB is a self-regulating body. It is not part of the United States government. It makes its own rules, and video game retailers and publishers choose whether or not to abide by them.
But since almost every retailer in America will not sell an unrated game or a game rated for adults only, there's a sort of forced compliance that publishers push onto the developers creating content for them. The same thing happens in the movie
However the resulting cuts imposed on games to achieve the acceptable 17 rating (named M or Mature) are usually minimal. Developers cut out 30 seconds of probably unnecessary violence, and the desired rating is given.
The Internet also offers a convenient way to bypass the ESRB altogether. If developers are that set in their vision, they can release the unaltered game online and sell it themselves. Sure, they won't get big studio funding for development and marketing,
but that's no different than movies, TV or the music industry.
Of course the compromise rating of 17 makes things a bit tricky for sexual content which would more naturally be rated 18. Hence as with movies, sexual content has nowhere to fit in the 'acceptable' ratings and ends up getting censored. This leads to the
effective situation where sexual themes are always rated more harshly than violence.