Adult video games are video games which have significant sexual content (like adult movies), and are therefore intended for an adult audience. Adult games can fall into many genres and have diverse gameplay.
PC and console
In console gaming, the genre can be seen as early as the Atari 2600, such as Custer's Revenge. In PCs, the genre can be first seen in adult text adventures, and later with graphical adventures, including one of the most recognized and mainstream adult adventure game series, Leisure Suit Larry. Arcade games have received few adult entries in North America.
With CD-ROM and multimedia based games in the 1990s, most adult games featured video clips with limited interactivity. Both pre-rendered and realtime 3D graphics were also used. While most games could be considered nothing more than pornography, some attempted to include actual story and plot. This can be seen in some games with less explicit content, equal to an R or PG-13 rated movie.
Modern console publishers often have policies against depictions of nudity and explicit sexuality, particularly Sony with its PlayStation brand of consoles. Some titles featuring nudity, such as BMX XXX and Leisure Suit Larry: Magna Cum Laude for the PlayStation 2 were censored, while versions on the Xbox and GameCube were not. However, Sony allowed nudity in the title God of War, which was also developed by Sony.
A new generation of adult social games has emerged that bring multiple users together in sexual environments. Examples include Red Light Center, Singles: Flirt Up Your Life and Playboy: The Mansion. While it is not explicitly intended for purely adult-oriented entertainment, the virtual world of Second Life, which is made up almost entirely of player-made content, has a very exotic array of adult entertainment including nudity and full-on sexual activities.
Adult games may take the form of bootlegs, circumventing mainstream publishers who may have policies against such games. Patches or hacks to mainstream non-adult games may add sexual and pornographic themes, mostly for humor, especially when sexuality was never intended in the original game. Examples include the Tomb Raider computer games, Grand Theft Auto: San Andreas' Hot Coffee mod, The Elder Scrolls IV: Oblivion (which has multiple such mods) and ROM hacks for console emulators. There is also a mod for World of Warcraft showing nude features.
The Internet has allowed adult games to receive wider availability and recognition, including amateur games in Flash or Java. It has also allowed amateurs to create and distribute adult text adventure games, known as "Adult Interactive Fiction" or AIF.
Japanese eroge (エロゲー erogē?), also known as hentai games, have their origins in the 1980s, when Japanese companies introduced their own brands of microcomputer to compete with those of the United States. Competing systems included the Sharp X1, Fujitsu FM-7, MSX, and NEC PC-8801. NEC was behind its competitors in terms of hardware (with only 16 colors and no sound support) and needed a way to regain control of the market. Thus came the erotic game. Early eroge had simple stories, often involving rape. It made the PC-8801 popular, but customers quickly tired of paying 8800 yen ($85) for such simple games. Soon, new genres were invented: ASCII's Chaos Angels, a role-playing-based eroge, inspired Dragon Knight by Elf and Rance by AliceSoft.
In 1992, Elf released Dōkyūsei. In it, before any eroticism, the user has to first win the affection of one of a number of female characters, making the story into an interactive romance novel. Thus, the love simulation genre was invented. Soon afterwards, the video game Otogirisou on the Super Famicom attracted the attention of many Japanese gamers. Otogirisou was a standard adventure game but had multiple endings. This concept was called a "sound novel."
In 1996, the new software publisher Leaf expanded on this idea, calling it a visual novel and releasing their first successful game, Shizuku, a horror story starring a rapist high school student, with very highly reviewed writing and music. Their next game, Kizuato, was almost as dark. However, in 1997, they released To Heart, a sweetly sentimental story of high school love that became one of the most famous and trendsetting eroge ever. To Heart's music was so popular it was added to karaoke machines throughout Japan — a first for eroge.
After a similar game by Tactics, One: Kagayaku Kisetsu e, became a hit in 1998, Visual Art's scouted main creative staff of One to form a new brand under them, which became Key. In 1999, Key released Kanon. It contains only about 7 brief erotic scenes in a sentimental story the size of a long novel (an all-ages version was also released afterward), but the enthusiasm of the response was unprecedented, and Kanon sold over 300,000 copies. In 2002 a 13-episode anime series was produced, as well as another 24-episode anime series in 2006. According to Satoshi TODOME's A History of Eroge, Kanon is still the standard for modern eroge and is referred to as a "baptism" for young otakus in Japan. Although many eroge still market themselves primarily on sex, eroge that focus on story are now a major established part of Japanese otaku culture.