Reversi


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 change to the board's initial setup, was patented in 1971.

Basics

There are sixty-four identical game pieces called disks, which are light on one side and dark on the other. Players take turns placing disks on the board with their assigned color facing up. During a play, any disks of the opponent's color that are in a straight line and bounded by the disk just placed and another disk of the current player's color are turned over to the current player's color. The object of the game is to have the majority of disks turned to display your color when the last playable empty square is filled.

History

Original version

Englishmen Lewis Waterman and John W. Mollett 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 nineteenth century. The game's first reliable mention is in 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." 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.

Othello

The modern version of the game—the most regularly used rule-set, and the one used in international tournaments—is marketed and recognized as Othello. It was patented in Japan in 1971 by , then a 38-year-old salesman.
The game differs from Reversi in that the first four pieces go in the center, but in a standard diagonal pattern, rather than being placed by players. Additionally, where Reversi ends as soon as either player cannot make a move, in Othello the player without a move simply passes.
Hasegawa established the Japan Othello Association on March 1973, and held the first national Othello championship on 4 April 1973 in Japan. 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.
The name was selected by Hasegawa as a reference to the Shakespearean play Othello, the Moor of Venice, referring to the conflict between the Moor Othello and Iago, and more controversially, 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, since players engulf the pieces of the opponent, thereby turning them to their possession.
Othello was first launched in the U.S. in 1975 by Gabriel Industries and it also enjoyed commercial success there. Reportedly, Othello game sales have exceeded $600 million and more than 40 million classic games have been sold in over 100 different countries.
Hasegawa also wrote How to Othello in Japan in 1974, which was later translated into English and published in the U.S. in 1977 as How to Win at Othello.
Kabushiki Kaisha Othello, which is owned by Hasegawa, registered the trademark "OTHELLO" for board games in Japan and Tsukuda Original registered the mark in the rest of the world. All intellectual property regarding Othello outside Japan is now owned by MegaHouse, a Japanese toy company that acquired PalBox, the successor to Tsukuda Original.

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.
For the specific game of Othello, the game begins with four disks placed in a square in the middle of the grid, two facing white-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, though this is only marginally consequential: where sequential openings' memorization is preferred, such players benefit from this. The dark player moves first.
Dark must place a piece on the board and so that there exists at least one straight 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:
Play always alternates. After placing a dark disk, dark turns over the single disk on the line between the new piece and an anchoring dark piece. 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.
If dark decided to put a piece in the topmost location, one piece gets turned over, so that the board appears thus:
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 :
Light takes the bottom left option and reverses one piece:
Players take alternate turns. If one player can not make a valid move, play passes back to the other player. When neither player can move, the game ends. This occurs when the grid has filled up or when neither player can legally place a piece in any of the remaining squares. This means the game may end before the grid is completely filled. This possibility may occur because one player has no pieces remaining on the board in that player's color. In over-the-board play this is generally scored as if the board were full.
Examples where the game ends before the grid is completely filled:
The player with the most pieces on the board at the end of the game wins. An exception to this is that if a clock is employed then if one player defaults on time that player's opponent wins regardless of the board configuration, with varying methods to determine the official score where one is required.
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 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 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 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 that has a through h left to right, and also that the perspective may be that of either player ), so that the very first move of a game may be d3, c4, f5 or e6. 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 play using ordinary sets rather than a computer interface—where this can not be an issue—have various ways of handling illegal moves and over- or underflipping. For example, permitting either player to make a correction going back some fixed number of moves is one procedure that has been used.
Significant variants of the game, such as where the starting position differs from standard or the objective is to have the fewest pieces one's color at the end, are sometimes—but rarely—played.

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 rounds W.O.C. Swiss, the tie is resolved in favour of the player with the higher Brightwell Quotient.
The Brightwell Quotient is calculated as follows:
  1. A constant c is calculated. It is the integer nearest to divided by.
  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 discs 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 to the result calculated in step 3. The number resulting is the player's BQ.

    Computer opponents and research

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 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.
Also the game has been particularly attractive to programmers.
Therefore, the best Othello computer programs have easily defeated the best humans since 1980, when the program The Moor beat the reigning world champion.
In 1997, Logistello defeated the human champion Takeshi Murakami with a score of 6–0.
Analysts have estimated the number of legal positions in Othello is at most 1028, and it has a game-tree complexity of approximately 1058. Mathematically, Othello still remains unsolved. Experts have not absolutely resolved what the outcome of a game will be where both sides use perfect play. However, analysis of thousands of high-quality games appears to lead to a reliable conclusion that, on the standard 8×8 board, perfect play on both sides results in a draw. 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. On 4×4 and 6×6 boards under perfect play, the second player wins. The first of these proofs is relatively trivial, and the second dates to around 1990.

World Othello Championship

YearLocationWorld ChampionTeamRunner-UpFemale ChampionYouth Champion
1977Tokyo Hiroshi InoueN/A Thomas HeibergN/AN/A
1978New York City Hidenori MaruokaN/A Carol JacobsN/AN/A
1979Rome Hiroshi InoueN/A Jonathan CerfN/AN/A
1980London Jonathan CerfN/A Takuya MimuraN/AN/A
1981Brussels Hidenori MaruokaN/A Brian RoseN/AN/A
1982Stockholm Kunihiko TanidaN/A David ShamanN/AN/A
1983Paris Ken'Ichi IshiiN/A Imre LeaderN/AN/A
1984Melbourne Paul RalleN/A Ryoichi TaniguchiN/AN/A
1985Athens Masaki TakizawaN/A Paolo GhirardatoN/AN/A
1986Tokyo Hideshi TamenoriN/A Paul RalleN/AN/A
1987Milan Ken'Ichi Ishii United States Paul RalleN/AN/A
1988Paris Hideshi Tamenori United Kingdom Graham BrightwellN/AN/A
1989Warsaw Hideshi Tamenori United Kingdom Graham BrightwellN/AN/A
1990Stockholm Hideshi Tamenori France Didier PiauN/AN/A
1991New York City Shigeru Kaneda United States Paul RalleN/AN/A
1992Barcelona Marc Tastet United Kingdom David ShamanN/AN/A
1993London David Shaman United States Emmanuel CaspardN/AN/A
1994Paris Masaki Takizawa France Karsten FeldborgN/AN/A
1995Melbourne Hideshi Tamenori United States David ShamanN/AN/A
1996Tokyo United Kingdom Stéphane NicoletN/AN/A
1997Athens Makoto Suekuni United Kingdom Graham BrightwellN/AN/A
1998Barcelona Takeshi Murakami France Emmanuel CaspardN/AN/A
1999Milan David Shaman Japan Tetsuya NakajimaN/AN/A
2000Copenhagen Takeshi Murakami United States Brian RoseN/AN/A
2001New York City Brian Rose United States Raphael SchreiberN/AN/A
2002Amsterdam David Shaman United States Ben SeeleyN/AN/A
2003Stockholm Ben Seeley Japan Makoto SuekuniN/AN/A
2004London Ben Seeley United States Makoto SuekuniN/AN/A
2005Reykjavík Hideshi Tamenori Japan Kwangwook Lee Hisako KinoshitaN/A
2006Mito Hideshi Tamenori Japan Makoto Suekuni Toshimi TsujiN/A
2007Athens Kenta Tominaga Japan Stéphane Nicolet Yukiko TatsumiN/A
2008Oslo Michele Borassi Japan Tamaki Miyaoka Liya YeN/A
2009Ghent Yusuke Takanashi Japan Matthias Berg Mei UrashimaN/A
2010Rome Yusuke Takanashi Japan Michele Borassi Jiska HelmesN/A
2011Newark Hiroki Nobukawa Japan Piyanat Aunchulee Jian CaiN/A
2012Leeuwarden Yusuke Takanashi Japan Kazuki Okamoto Veronica StenbergN/A
2013Stockholm Kazuki Okamoto Japan Piyanat Aunchulee Katie WuN/A
2014Bangkok Makoto Suekuni Japan Ben Seeley Joanna WilliamN/A
2015Cambridge Yusuke Takanashi Japan Makoto Suekuni Yoko Sano RoseN/A
2016Mito Piyanat Aunchulee Japan Yan Song Zhen Dong Masaki Wada
2017Ghent Yusuke Takanashi Japan Akihiro Takahashi Misa Sugawara Akihiro Takahashi
2018Prague Keisuke Fukuchi Japan Piyanat Aunchulee Misa Sugawara Keisuke Fukuchi
2019Tokyo Akihiro Takahashi Japan Yusuke Takanashi Joanna William Akihiro Takahashi