Popular video game streaming service (and Amazon subsidiary) Twitch has updated its rules of conduct to prohibit the streaming of games rated AO (Adults Only) by the Entertainment Software Rating Board (ESRB). "Simply put, AO games are not welcome on Twitch," the site said in an official blog post.

The update is a clarification of previous game-specific bans Twitch placed on streaming of titles that featured "overtly sexual content" or "gratuitous violence." That system was "unsustainable and unclear, generating only further confusion among Twitch broadcasters," the company said in its blog post last night. "We would like to make this policy as transparent as possible." Players breaking the ban will receive a temporary suspension.

Twitch's new policy comes ahead of the impending release of Hatred , a controversial shooter that received an AO rating back in January , according to developer Destructive Creations. In fact,is one of three AO-rated games specifically called out on Twitch's list of prohibited games , alongsideand

With somewhat confusing wording, Twitch adds that "Mature rated versions of Adults Only titles" are allowed on the service, meaning the original Indigo Prophecy is OK even though the AO-rated "Director's Cut" is not. The re-cut, M-rated version of Grand Theft Auto: San Andreas is also OK, even though the AO-rated original release is prohibited. Frankly, we have to wonder how anyone will tell the difference between the two versions unless the streamer hacks his or her way into some "hot coffee."

Games rated as 18+ or the equivalent by other rating systems are OK to stream "so long as they are not rated AO by the ESRB, and they don’t violate the standard language of our RoC and ToS," Twitch says. For games not rated by the ESRB, we can only assume Twitch's existing prohibitions on nudity and sexually explicit acts in games will still apply.

Aside from the few dozen titles that have received an AO from the ESRB, Twitch specifically bans five other titles that don't meet its content guidelines. That list includes the M-rated, T&A-filled biking game BMXXX, MMO Second Life, visual novels Dramatical Murder and Sakura Spirit, and explicit dating sim/puzzle game HuniePop.