Although Go is an ancient board game dated back to 2357 - 2255 B.C., Go on the 9 x 9 board has been created and become popular since that past few decades.

Nobody really knows when and where the origin of 9 x 9 Go is. I found no evidence to indicate the exact year when the game was invented and the person who invented it. The oldest 9 x 9 game records seem to be the two games between Go Seigen 9p and Miyamoto Naoki 8p in 1968 [1]. By then, the most common board sizes are 8 x 8, 13 x 13, 17 x 17, apart from 19 x 19 [2]. Karl Baker also uses the 8 x 8 board size as illustrations in his book, The Way to Go.

Kamada Masahito has studied the changes of 9 x 9 opening moves in 846 games of the Japanese players. The oldest game was played in the year 1968.

Great Britain & Japan

In Great Britain, Francis Roads noted in 1971 that they have experienced playing on the 13 x 13 and 10 x 10 boards [3]. This statement confirms that the 9 x 9 Go was not common prior to 1970. Mr. Roads is among the first to raise the status of the 9 x 9 game, by writing the first article about 9 x 9 Go published in British Go Journal, No. 66 (November, 1985). Three years later, Cho Chikun 9p, the strongest 9 x 9 human Go player in history, too, encouraged the use of 9 x 9 Go for learning the basic of Go, as noted in his book, The Magic of Go, in 1988.

About in the same period, popularity of 9 x 9 Go was boost in Japan by Yomiuri TV's MiniGo matches from 1987 to 2002.

Global

In the global scale, 9 x 9 Go has gained in popularity since the late 1990s, after David Fortland published Igowin for Windows—the strongest free 9 x 9 Go program at that time. He decides to write a go playing program in 1981. Three years later, the first Computer Go Tournament in the US was organized by Peter Langston as part of the 1984 Usenix conference. In the same year, Acornsoft Computer Go Tournament was held in London by the British Go Association. Five years later, the Computer Go Olympiad, organized by the International Computer Games Association (ICCA) was started in 1989 for 9 x 9 boards, with the initial tournaments held in London and won by Dragon Go. Hence, 9 x 9 Go had been a subject for computer go study before 1989 yet after 1977, because ICCA was founded in 1977.

Michael Reiss started writing GO++ in 1983 that became the strongest computer Go programs in 1999, when winning the ING Cup that year by beating all its opponents, including Handtalk--a long time world champion among go programs, from 1993 to 1997.

Fortland's full strength Go program, Many Faces of Go, is the first commercial Go program. This Go engine has been employed in the iPad app called Igowin HD, with the maximum strength of 1 Kyu, or 1 Dan GoQuest. If any player defeats it 10 games in a row, Igowin HD will promote him or her to be 8-Dan at most.

In the early 2000s, 9 x 9 Go has become even more popular when people could play Go with stronger players at Yahoo! Games, where there were 9 x 9 Go Rooms for beginners and advanced players.

In 2009, Fuego was the first computer program that won an official game of 9 x 9 Go against a 9-Dan professional player, Zhou Junxun, at the Fuzz IEEE 2009 conference. The game record is given at the conference webpage. See Enzenbeger and Muller (2009) for technical report.

In the smart phone age, since 2010, a more popular 9 x 9 Go server has become GoQuest by Yasushi Tanase, and then Yahoo! Games was closed down on March 31, 2014. More than 30,000 users are active 9 x 9 players on GoQuest, with around 25,000 kyu players (Elo<1700). Many of them have played more than 10,000 matches but cannot yet break through to Shodan, even the minimal rating requirement for Shodan promotion has been relaxed from 1750 to 1700. Superhuman players, especially those who were the number one ranked players and can defeat :AyaXBot with ease, might have been inactivated by the admin, like me (Kingof9 and 9x9Meijin), who once defeated spaceman 9-Dan or Ohashi Hirofumi 6p in the superhuman performance analysis experiment conducted on January 28, 2020.

Another popular 9 x 9 Go server is Go Wars, where there is a stronger Go bot called Kishin. The rating system here is more suppressive. The 7-Dan player here is stronger than the 8-Dan player at GoQuest.

Strong Computer Go Programs

In 2008, Mogo defeated Catalin Taranu 5p, and is the first computer Go program to win as Black against a pro. See the technical report in Gelly and Silver (2008).

In 2009, MogoTW defeated Chun-Hsun Chou 9p, who won the LG Cup 2007. So, MoGoTW is the first program to win as Black againts a top pro, according to Billouet et al. (2009) In the same year, as noted above, Fuego was the first computer program that won an official game of 9 x 9 Go against a 9-Dan professional player, Zhou Junxun, at the Fuzz IEEE 2009 conference.

In May 2019, SAI defeated Hayashi Kozo 6p and Oh Chimin 7D with the bonus handicap of 6 points. According to expert Go knowledge, winning against a professional Go player with 6 points of handicap on a 9 x 9 board is an achievement that classifies SAI as superhuman (Morandin et al., 2019).

However, there are other superhuman Go programs released in 2020, which play 9 x 9 Go better than SAI (e.g., Go Master tested by da Westi, 2020).

NOTES

[1] The game records can be downloaded at gobase.org

[2] Noted in 1969 by Scott A. Boorman in The Protracted Game: A Wei-Chi Interpretation of Maoist Revolutionary Strategy.

[3] For more information, see British Go Journal , April 1971 issue, Page 11.