The AO rating explained: what Adults Only means and why almost no game has it

AO stands for “Adults Only 18+”. It is the highest rating given by the Entertainment Software Rating Board (ESRB), which rates games in the United States and Canada. An AO rating means the ESRB considers a game suitable only for adults aged 18 and over. In practice it also means the game cannot be sold on any console and will not be stocked by most shops, which is why almost no game carries it.

This page explains what the rating covers, how it differs from M, why it is so rare, and why the thousands of adult games on PC are mostly not AO-rated at all.

Key points

• AO is the ESRB’s top rating: adults aged 18 and over only.
• It is one year above M (Mature 17+), but the commercial difference is enormous.
• Nintendo, Sony and Microsoft do not allow AO games on their consoles.
• Only 23 released games have carried the rating since 1994.
• ESRB ratings are voluntary. Most adult PC games have never been rated by the ESRB.
• Steam’s “Adult Only Sexual Content” label is Steam’s own. It is not an AO rating.

What the AO rating means

The ESRB’s ratings guide defines its two highest ratings as follows.

Three things can lead to an AO, and the definition names all of them.

• Graphic sexual content. This is the usual reason. M allows “sexual content”; AO is for content that is graphic.
• Prolonged, intense violence. This is rare. Only a handful of games have been rated AO for violence alone.
• Gambling with real money. A game in which players bet real currency is rated AO whatever else it contains.

The AO rating has existed since the ESRB began. The board was founded on 16 September 1994, after hearings in the United States Congress about violent games such as Mortal Kombat and Night Trap, and its original set of ratings already included Adults Only.

AO vs M: one year, and a wall

On paper the two ratings are a year apart: 17 and 18. In the market they are separated by a wall.

An M-rated game is an ordinary commercial product. Many of the best-selling games ever made are rated M. An AO-rated game has almost nowhere to be sold, for the reasons below.

Why almost no game is rated AO

The ESRB does not ban anything. The rating is rare because of what other companies do when they see it.

Console makers refuse it

All three console makers have a policy against AO games. As Wikipedia’s list of AO-rated games records, Nintendo “does not sell or license games that carry the ESRB rating ‘AO’”, Microsoft “does not support AO titles”, and Sony “does not publish Adults Only games”.

A console game cannot be released without the console maker’s licence. So an AO rating removes PlayStation, Xbox and Switch in a single step.

Retailers refuse it

Large retailers in North America have long declined to stock AO games. When one game was re-rated to AO in 2005, Walmart, Target, Best Buy and Circuit City all stopped selling it at once. That case is described below.

Streaming platforms refuse it

In May 2015 Twitch changed its rules to ban the streaming of AO-rated games outright. A game that cannot be streamed loses one of the main ways games are now discovered.

Publishers edit to avoid it

Faced with those three walls, publishers change the game. A publisher that is told a game will receive an AO edits the content and resubmits it until it receives an M. The rating has been called a “kiss of death” for this reason: it works as a ban in practice, although it is only a label.

The games that were rated AO

Wikipedia’s list counts 23 released games with an AO rating. Most are little-known PC titles with sexual content. The cases that shaped the rating’s reputation are these.

Grand Theft Auto: San Andreas (2005)

This is the best-known case. San Andreas was released in October 2004 with an M rating. In June 2005 a modder published a patch, known as Hot Coffee, that unlocked an unfinished sexual minigame left in the game’s files.

• 20 July 2005: the ESRB changed the rating from M to AO.
• Walmart, Target, Best Buy and Circuit City announced they would stop selling the game immediately.
• August to November 2005: patched and re-released versions without the content returned to an M rating.
• The recall cost the publisher, Take-Two, $24.5 million.

In June 2006 the ESRB began requiring publishers to disclose content that is on the disc but not normally reachable.

Manhunt 2 (2007)

Manhunt 2 was given an AO for violence. Its publisher edited the console versions to reach an M before release. An uncut version for PC followed in 2009 and kept the AO rating.

Fahrenheit, or Indigo Prophecy (2005)

The North American release had its sex scenes edited out to reach an M rating.

Hatred (2015)

Hatred received an AO in January 2015 for extreme violence. It is one of only three games rated AO for violence alone, alongside the PC version of Manhunt 2 and Thrill Kill, a 1998 fighting game that was cancelled before release.

Peak Entertainment Casinos (2003)

This is the only game rated AO for a reason other than sex or violence. It allowed gambling with real money.

Is the AO rating a legal requirement?

No. ESRB ratings are voluntary. No law in the United States requires a game to be rated, and no law stops a shop from selling an AO game to an adult.

In 2011, in Brown v. Entertainment Merchants Association, the United States Supreme Court struck down a California law restricting the sale of violent games to minors and held that video games are protected speech. The rating system is run by the industry, and its force comes from the policies of console makers and retailers.

Why most adult games are not AO-rated

This is the part that confuses people. There are thousands of adult games on PC, far more than 23. Almost none of them are rated AO, because almost none of them have been rated by the ESRB at all.

A physical console game needs an ESRB rating to be licensed and stocked. A PC game sold as a download does not. The stores where adult games are sold use their own systems.

• Steam does not require an ESRB rating. Developers fill in a content survey, and games with explicit content receive the descriptor “Adult Only Sexual Content”. It is hidden by default, and a customer has to confirm they are 18 to see it. The name resembles the ESRB’s, but it is a store label. See how to see adult games on Steam.
• itch.io uses a “sensitive material” setting and adult tags.
• Specialist stores for adult games label everything they sell as adult.

So the question “which games on Steam are AO-rated?” has a short answer. A very small number of games that were once rated AO by the ESRB have been sold on PC. The adult games that players mean are a different group: unrated by the ESRB and labelled by the store.

The other labels players use for these games are covered in what NSFW means for games.

AO games on phones

App stores use a different route to ratings. Since 2012 the International Age Rating Coalition has offered a free questionnaire that produces ratings for several boards at once, including the ESRB, for digital storefronts.

That does not open the door to AO games. Google Play’s content policy bans apps with sexual content meant to arouse, and Apple’s rules do the same. Why that is, and how adult games reach phones anyway, is covered in adult games on Android and iPhone.

AO and other countries

The ESRB covers the United States and Canada. Other regions have their own boards, and they do not all have a separate adults-only tier.

In Europe, PEGI’s highest label is PEGI 18. There is nothing above it, so a game rated M in North America and a game rated AO would both be PEGI 18 if PEGI rated them. This is one reason the AO rating matters much less outside North America: the wall between “mature” and “adults only” is an ESRB feature.

What this means for players and developers

For players, the AO rating is not a useful way to find adult games. Search by the store’s own label instead: Steam’s adult content setting, itch.io’s adult filter, or a specialist store.

For developers, the rating is mostly irrelevant unless you plan a console release. If you do, the content has to fit an M, which means no graphic sexual content. A PC release needs no ESRB rating. What it does need is to meet the rules of the store and of the companies that process its payments, which are now the stricter test. Those rules are set out in how payment processors decide which adult games can exist and where adult games can be sold.