Reversi

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Reversi is a strategy board game for two players, played on an 8×8 uncheckered board. It was invented in 1883. Othello, a variant with a fixed initial setup of the board, was patented in 1971.

Basics

Two players compete, using 64 identical game pieces ("disks") that are light on one side and dark on the other. Each player chooses one color to use throughout the game. Players take turns placing one disk on an empty square, with their assigned color facing up. After a play is made, any disks of the opponent's color that lie in a straight line bounded by the one just played and another one in the current player's color are turned over. When all playable empty squares are filled, the player with more disks showing in their own color wins the game.

History

File:Nintendo-TV-Game-Computer.jpg

Othello was one of Nintendo's first arcade games, and it was later ported to a dedicated home game console in 1980.

Original version

Englishmen Lewis Waterman and John W. MollettTemplate:Citation needed both claim to have invented the game of reversi in 1883, each denouncing the other as a fraud. The game gained considerable popularity in England at the end of the 19th century.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The game's first reliable mention is in the 21 August 1886 edition of The Saturday Review. Later mention includes an 1895 article in The New York Times, which describes reversi as "something like Go Bang, [...] played with 64 pieces."<ref name="NYT">Template:Cite news</ref> In 1893, the German games publisher Ravensburger started producing the game as one of its first titles. Two 18th century continental European books dealing with a game that may or may not be reversi are mentioned on page fourteen of the Spring 1989 Othello Quarterly, and there has been speculation, so far without documentation, that the game has older origins.Template:Citation needed

A Japanese publication in 1907 titled World Games Rules Complete Collection (世界遊戯法大全) describes the board game reversi with the same rules as Othello where the first four pieces go in the center in a diagonal pattern and the player who cannot make a move simply passes.<ref>Template:Cite book</ref>

Othello

File:Othello (Reversi) board.jpg

A modern plastic Othello set

The modern version of the game—the most regularly used rule-set, and the one used in international tournaments—is marketed and recognized as Template:Nihongo. It was patented in Japan in 1971 by Goro Hasegawa (legal name: Satoshi Hasegawa), then a 38-year-old salesman.<ref>See Japan Utility Patent Application numbers S46-001435 (JP,1971-001435) and number S47-135869 (JP,1972-135869), available via https://www.j-platpat.inpit.go.jp/web/all/top/BTmTopEnglishPage</ref><ref>Template:Cite magazine</ref> Hasegawa initially explained that Othello was an improvement on reversi,<ref>Template:Cite journal</ref> but from around 2000, he began to claim that he invented it in Mito regardless of reversi.<ref>Template:Cite book</ref> Hasegawa also claimed that the origin of reversi/Othello dates back 5,000 years.<ref>Template:Cite book</ref>

Hasegawa established the Japan Othello Association in March 1973, and held the first national Othello championship on 4 April 1973 in Japan.<ref>The Nihon Keizai Shimbun. Page 24, 20 March 1973</ref> The Japanese game company Tsukuda Original launched Othello in late April 1973 in Japan under Hasegawa's license, which led to an immediate commercial success.<ref name="FFOhistory">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Pages 147–151 of The December issue of GENDAI, published by Kodansha on 1 December 1973. Viewed at National Diet Library of Japan</ref><ref>Pages 110–113 August 25 issue of Yomiuri Weekly, published by Yomiuri Shimbun on 25 August 1973. Viewed at National Diet Library of Japan</ref><ref>Page 23 of Vol.77, No.1811 of JITSUGYO NO NIHON published by Jitsugyo no Nihon Sha, Ltd. on 1 March 1974. Viewed at National Diet Library of Japan</ref><ref name=":0">Pages 276–281 December issue of The Ushio published by Ushio Publishing Co., Ltd., on 1 December 1974. Viewed at National Diet Library of Japan</ref>

The name was selected by Hasegawa<ref name=":0" /> as a reference to the Shakespearean play Othello, the Moor of Venice, referring to the conflict between the Moor Othello and Iago, and to the unfolding drama between Othello, who is black, and Desdemona, who is white. The green color of the board is inspired by the image of the general Othello, valiantly leading his battle in a green field. It can also be likened to a jealousy competition (jealousy being the central theme in Shakespeare's play, which popularized the term "green-eyed monster"), since players engulf the pieces of the opponent, thereby turning them to their possession.<ref>Template:Cite magazine</ref>

Othello was first launched in the U.S. in 1975 by Gabriel Industries and it also enjoyed commercial success there. Sales have reportedly exceeded $600 million. More than 40 million classic games have been sold in over 100 countries.

Hasegawa's How to play Othello (Osero No Uchikata) in Japan in 1974, was published in 1977 in an English translation entitled How to Win at Othello.<ref>Template:Cite book</ref>

Kabushiki Kaisha Othello, which was owned by Hasegawa, registered the trademark "OTHELLO" for board games in Japan; Tsukuda Original registered the trademark in the rest of the world. All intellectual property regarding Othello outside Japan is now owned by MegaHouse, the Japanese toy company that acquired Tsukuda Original's successor PalBox.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Rules

Each of the disks' two sides corresponds to one player; they are referred to here as light and dark after the sides of Othello pieces, but any counters with distinctive faces are suitable. The game may for example be played with a chessboard and Scrabble pieces, with one player letters and the other backs.

The historical version of reversi starts with an empty board, and the first two moves made by each player are in the four central squares of the board. The players place their disks alternately with their colors facing up and no captures are made. A player may choose to not play both pieces on the same diagonal, different from the standard Othello opening. It is also possible to play variants of Reversi and Othello where the second player's second move may or must flip one of the opposite-colored disks (as variants closest to the normal games).

For the specific game of Othello, the game begins with four disks placed in a square in the middle of the grid, two facing light-side-up, two dark-side-up, so that the same-colored disks are on a diagonal. Convention has this such that the dark-side-up disks are to the north-east and south-west (from both players' perspectives), though this is only marginally consequential: where sequential openings' memorization is preferred, such players benefit from this. The dark player moves first. Template:Reversi Dark must place a piece (dark-side-up) on the board and so that there exists at least one straight (horizontal, vertical, or diagonal) occupied line between the new piece and another dark piece, with one or more contiguous light pieces between them. For move one, dark has four options shown by translucently drawn pieces below: Template:Reversi Play always alternates unless one player has no legal move, in which case they pass. After placing a dark disk, dark turns over (flips to dark, captures) the single disk (or chain of light disks) on the line between the new piece and an anchoring dark piece. Multiple chains of disks may be captured in a single move. No player can look back to the previous status of disks when playing moves. A valid move is one where at least one piece is reversed (flipped over).

If dark decided to put a piece in the topmost location (all choices are strategically equivalent at this time), one piece gets turned over, so that the board appears thus: Template:Reversi Now light plays. This player operates under the same rules, with the roles reversed: light lays down a light piece, causing a dark piece to flip. Possibilities at this time appear thus (indicated by transparent pieces): Template:Reversi Light takes the bottom left option and reverses one piece: Template:Reversi Players take alternate turns. If one player cannot make a valid move, play passes back to the other player. The game ends when the grid has filled up or if neither player can make a valid move.

Examples where the game ends before the grid is completely filled: Template:Reversi

The player with the most pieces on the board at the end of the game wins. The game is scored by counting the number of discs in each player's color. If the game ended before the grid was completely filled, any empty squares are scored for the winner.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> However, if one player defaults by running out of time, that player's opponent wins regardless of the board configuration. There are varying methods to determine the official score when a player defaults.

In common practice over the Internet, opponents agree upon a time-control of, typically, from one to thirty minutes per game per player. Standard time control in the World Championship is thirty minutes, and this or something close to it is common in over-the-board (as opposed to internet) tournament play generally. In time-defaulted games, where disk differential is used for tie-breaks in tournaments or for rating purposes, one common over-the-board procedure for the winner of defaulted contests to complete both sides' moves with the greater of the result thereby or one disk difference in the winner's favor being the recorded score. Games in which both players have the same number of disks their color at the end (almost always with a full-board 32–32 score) are not very common, but also not rare, and these are designated as 'ties' and scored as half of a win for each player in tournaments. The term 'draw' for such may also be heard, but is somewhat frowned upon.

What are generally referred to as transcript sheets are generally in use in tournament over-the-board play, with both players obligated to record their game's moves by placing the number of each move in an 8×8 grid. This both enables players to look up past games of note and tournament directors and players to resolve disputes (according to whatever specific rules are in place) where claims that an illegal move, flip or other anomaly are voiced. An alternative recording method not requiring a grid is also in use, where positions on a board are labeled left to right by letters a through h and top to bottom by digits 1 through 8. Note that the numbers run in the opposite direction to the chess standard, and that the perspective may be that of either player (with no fixed standard). This alternate notational scheme is used primarily in verbal discussions or where a linear representation is desirable in print, but may also be permissible as during-game transcription by either or both players.

Tournament over-the-board play has various ways of handling illegal moves and incorrect flips. For example, one procedure that has been used is to permit either player to make corrections going back some fixed number of moves.

Anti-Reversi

Anti-Reversi or Reversed Reversi is a variant of the game where the player wins who has fewer own-colored disks at the end of the game; draw is also a possible result.<ref>About Anti-Reversi https://samsoft.org.uk/reversi/strategy.htm on 14 August 2024</ref> To put a disk on the board, the same rules apply as in normal reversi.

Brightwell Quotient

Invented by the British mathematician and three times runner-up at the World Championship and five times British Champion Graham Brightwell, this is the tie-breaker that is now used in many tournaments including the W.O.C. If two players have the same number of points in the thirteen-round W.O.C. Swiss, the tie is resolved in favour of the player with the higher Brightwell Quotient.Template:Cn

The Brightwell Quotient (BQ) is calculated as follows:<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

1. A constant c is calculated. It is the integer nearest to (number of squares on the board) divided by (number of rounds in the tournament).
2. If any of the player's opponents have withdrawn in the course of the tournament, or if a player has been paired against bye, ignore such games for the moment.
3. Calculate the total number of disks scored by the player in all games not covered by step 2 and add c times the sum of points scored by all of the player's opponents, except those who have withdrawn.
4. For each game against an opponent who has withdrawn, and each bye received, add half the number of squares on the board plus (c times the player's own tournament score) to the result calculated in step 3. The number resulting is the player's BQ.

Computer opponents and research

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Good Othello computer programs play very strongly against human opponents. This is mostly due to difficulties in human look-ahead peculiar to Othello: The interchangeability of the disks and therefore apparent strategic meaninglessness (as opposed to chess pieces for example) makes an evaluation of different moves much harder. This can be demonstrated with blindfold games, as the memorization of the board demands much more dedication from the players than in blindfold chess.

The first tournament pitting Othello computer programs against human opponents took place in 1980. In it, then world champion Hiroshi Inoue, although he would go on to win the tournament, lost a game against the computer program The Moor. In 1997, the computer Othello program Logistello defeated the reigning human champion, Takeshi Murakami, six games to zero.<ref>Template:Cite book</ref>

Analysts have estimated the number of legal positions in Othello is at most 10²⁸, and it has a game-tree complexity of approximately 10⁵⁸.<ref name="Allis1994">Template:Cite book</ref> Mathematically, Othello is solved up to 8x8 board. On 4×4 and 6×6 boards under perfect play, the second player wins.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> On 8x8 board, the game results in draw under perfect play, according to an arXiv paper.<ref>Template:Cite arXiv</ref> The first of these proofs is relatively trivial, the second dates to around 1990, and the last one was done in 2023. When generalizing the game to play on an n×n board, the problem of determining if the first player has a winning move in a given position is PSPACE-complete.<ref>Template:Cite journal</ref>

World Othello Championship

The World Othello Championship (WOC), which started in 1977, was first organized by the Japan Othello Association. From 1978 until 2004, the World Othello Championship was organized by the Othello TD group and Anjar Co. In 2005, the World Othello Federation took over the responsibility for the WOC.

From 1977 to 1986, each country could send one player to participate in the WOC. From 1987, each country could send up to three players to participate. In 1987, the title WOC team championship started. In 2005, a female championship category was added to the WOC. From 2006, each World Othello Federation member could send a full team of up to four players. In 2016, a youth champion title was added to the WOC.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The WOC was cancelled in 2020 and 2021 due to the COVID-19 pandemic.

Year	Location	World Champion	Team	Runner-up	Female Champion	Youth Champion
1977	Tokyo	Template:Flagicon Hiroshi Inoue	N/A	Template:Flagicon Thomas Heiberg	N/A	N/A
1978	New York City	Template:Flagicon Hidenori Maruoka	N/A	Template:Flagicon Carol Jacobs	N/A	N/A
1979	Rome	Template:Flagicon Hiroshi Inoue	N/A	Template:Flagicon Jonathan Cerf	N/A	N/A
1980	London	Template:Flagicon Jonathan Cerf	N/A	Template:Flagicon Takuya Mimura	N/A	N/A
1981	Brussels	Template:Flagicon Hidenori Maruoka	N/A	Template:Flagicon Brian Rose	N/A	N/A
1982	Stockholm	Template:Flagicon Kunihiko Tanida	N/A	Template:Flagicon David Shaman	N/A	N/A
1983	Paris	Template:Flagicon Ken'Ichi Ishii	N/A	Template:Flagicon Imre Leader	N/A	N/A
1984	Melbourne	Template:Flagicon Paul Ralle	N/A	Template:Flagicon Ryoichi Taniguchi	N/A	N/A
1985	Athens	Template:Flagicon Masaki Takizawa	N/A	Template:Flagicon Paolo Ghirardato	N/A	N/A
1986	Tokyo	Template:Flagicon Hideshi Tamenori	N/A	Template:Flagicon Paul Ralle	N/A	N/A
1987	Milan	Template:Flagicon Ken'Ichi Ishii	Template:Flagicon United States	Template:Flagicon Paul Ralle	N/A	N/A
1988	Paris	Template:Flagicon Hideshi Tamenori	Template:Flagicon United Kingdom	Template:Flagicon Graham Brightwell	N/A	N/A
1989	Warsaw	Template:Flagicon Hideshi Tamenori	Template:Flagicon United Kingdom	Template:Flagicon Graham Brightwell	N/A	N/A
1990	Stockholm	Template:Flagicon Hideshi Tamenori	Template:Flagicon France	Template:Flagicon Didier Piau	N/A	N/A
1991	New York City	Template:Flagicon Shigeru Kaneda	Template:Flagicon United States	Template:Flagicon Paul Ralle	N/A	N/A
1992	Barcelona	Template:Flagicon Marc Tastet	Template:Flagicon United Kingdom	Template:Flagicon David Shaman	N/A	N/A
1993	London	Template:Flagicon David Shaman	Template:Flagicon United States	Template:Flagicon Emmanuel Caspard	N/A	N/A
1994	Paris	Template:Flagicon Masaki Takizawa	Template:Flagicon France	Template:Flagicon Karsten Feldborg	N/A	N/A
1995	Melbourne	Template:Flagicon Hideshi Tamenori	Template:Flagicon United States	Template:Flagicon David Shaman	N/A	N/A
1996	Tokyo	Template:Flagicon Takeshi Murakami	Template:Flagicon United Kingdom	Template:Flagicon Stéphane Nicolet	N/A	N/A
1997	Athens	Template:Flagicon Makoto Suekuni	Template:Flagicon United Kingdom	Template:Flagicon Graham Brightwell	N/A	N/A
1998	Barcelona	Template:Flagicon Takeshi Murakami	Template:Flagicon France	Template:Flagicon Emmanuel Caspard	N/A	N/A
1999	Milan	Template:Flagicon David Shaman	Template:Flagicon Japan	Template:Flagicon Tetsuya Nakajima	N/A	N/A
2000	Copenhagen	Template:Flagicon Takeshi Murakami	Template:Flagicon United States	Template:Flagicon Brian Rose	N/A	N/A
2001	New York City	Template:Flagicon Brian Rose	Template:Flagicon United States	Template:Flagicon Raphael Schreiber	N/A	N/A
2002	Amsterdam	Template:Flagicon David Shaman	Template:Flagicon United States	Template:Flagicon Ben Seeley	N/A	N/A
2003	Stockholm	Template:Flagicon Ben Seeley	Template:Flagicon Japan	Template:Flagicon Makoto Suekuni	N/A	N/A
2004	London	Template:Flagicon Ben Seeley	Template:Flagicon United States	Template:Flagicon Makoto Suekuni	N/A	N/A
2005	Reykjavík	Template:Flagicon Hideshi Tamenori	Template:Flagicon Japan	Template:Flagicon Kwangwook Lee	Template:Flagicon Hisako Kinoshita	N/A
2006	Mito	Template:Flagicon Hideshi Tamenori	Template:Flagicon Japan	Template:Flagicon Makoto Suekuni<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref> || Template:Flagicon Toshimi Tsuji || N/A
2007	Athens	Template:Flagicon Kenta Tominaga	Template:Flagicon Japan	Template:Flagicon Stéphane Nicolet	Template:Flagicon Yukiko Tatsumi	N/A
2008	Oslo	Template:Flagicon Michele Borassi	Template:Flagicon Japan	Template:Flagicon Tamaki Miyaoka	Template:Flagicon Liya Ye	N/A
2009	Ghent	Template:Flagicon Yusuke Takanashi	Template:Flagicon Japan	Template:Flagicon Matthias Berg	Template:Flagicon Mei Urashima	N/A
2010	Rome	Template:Flagicon Yusuke Takanashi	Template:Flagicon Japan	Template:Flagicon Michele Borassi	Template:Flagicon Jiska Helmes	N/A
2011	Newark	Template:Flagicon Hiroki Nobukawa	Template:Flagicon Japan	Template:Flagicon Piyanat Aunchulee	Template:Flagicon Jian Cai	N/A
2012	Leeuwarden	Template:Flagicon Yusuke Takanashi	Template:Flagicon Japan	Template:Flagicon Kazuki Okamoto	Template:Flagicon Veronica Stenberg	N/A
2013	Stockholm	Template:Flagicon Kazuki Okamoto	Template:Flagicon Japan	Template:Flagicon Piyanat Aunchulee	Template:Flagicon Katie Wu	N/A
2014	Bangkok	Template:Flagicon Makoto Suekuni	Template:Flagicon Japan	Template:Flagicon Ben Seeley	Template:Flagicon Joanna William	N/A
2015	Cambridge	Template:Flagicon Yusuke Takanashi	Template:Flagicon Japan	Template:Flagicon Makoto Suekuni	Template:Flagicon Yoko Sano Rose	N/A
2016	Mito	Template:Flagicon Piyanat Aunchulee	Template:Flagicon Japan	Template:Flagicon Yan Song	Template:Flagicon Zhen Dong	Template:Flagicon Masaki Wada
2017	Ghent	Template:Flagicon Yusuke Takanashi	Template:Flagicon Japan	Template:Flagicon Akihiro Takahashi	Template:Flagicon Misa Sugawara	Template:Flagicon Akihiro Takahashi
2018	Prague	Template:Flagicon Keisuke Fukuchi	Template:Flagicon Japan	Template:Flagicon Piyanat Aunchulee	Template:Flagicon Misa Sugawara	Template:Flagicon Keisuke Fukuchi
2019	Tokyo	Template:Flagicon Akihiro Takahashi	Template:Flagicon Japan	Template:Flagicon Yusuke Takanashi	Template:Flagicon Joanna William	Template:Flagicon Akihiro Takahashi
2020	Cancelled
2021	Cancelled
citation	CitationClass=web }}</ref> || Paris || Template:Flagicon Kento Urano || Template:Flagicon Japan || Template:Flagicon Arthur Juigner || Template:Flagicon Katie Pihlajapuro || Template:Flagicon Fuyumi Okudaira
citation	CitationClass=web }}</ref> || Rome || Template:Flagicon Yasushi Nagano || Template:Flagicon Japan || Template:Flagicon Rujipas Aunchulee || Template:Flagicon Hisako Kinoshita || Template:Flagicon Osuke Kawazoe
citation	CitationClass=web }}</ref> || Hangzhou || Template:Flagicon Seiya Kurita || Template:Flagicon Japan || Template:Flagicon Yusuke Takanashi || Template:Flagicon Hisako Kinoshita || Template:Flagicon Yo Tomita

Reception

Games magazine included Othello in their "Top 100 Games of 1980", noting that it was "Based on the Victorian game of reversi" and had achieved "remarkable success in this country for an abstract game of strategy".<ref>Template:Cite magazine</ref>

Games magazine included Othello, Tournament Set in their "Top 100 Games of 1981", noting that by that time "Othello has become so popular that Gabriel now markets a computer version and a players' association publishes a quarterly magazine".<ref>Template:Cite magazine</ref>

Games magazine included Othello in their "Top 100 Games of 1982", noting that "Although the goal is to finish with the most pieces of your color up, the best strategy, paradoxically, is usually to limit your opponent's options by flipping over as few of his discs as possible during the first two-thirds of the game."<ref>Template:Cite magazine</ref>

Reviews

• Games #1<ref>{{#invoke:citation/CS1|citation

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• Template:Ill #6<ref>{{#invoke:citation/CS1|citation

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• Family Games: The 100 Best<ref>Template:Cite book</ref>

See also

• Reversi Champion

External links

• "Othello (Reversi)", University of Waterloo, Elliott Avedon Museum & Archive of Games
• Brian Rose, Othello: A Minute to Learn... A Lifetime to Master, 2005.
• British Othello Federation Newsletters
• Emmanuel Lazard and Federation Francaise d'Othello, "Othello: The Rules of the Game", 1993.
• Template:Bgg
• Pictures of the 19th century reversi boards
• Randy Fang, Othello: From Beginner to Master, 2003.
• Reversi – An Animated Guide
• Ted Landau, Othello: Brief & Basic, 1990.
• World Othello Federation
• World Othello Rating List
• Reversi Game Online