Reversi

Reversi is a two player board game invented in England in 1883 by the Englishman Lewis Waterman, and was popular in England at the end of the 19th century. The modern rules, now universally accepted, originated in Mito, Ibaraki, Japan in the 1970s; when the game was renamed Othello, and was registered as a trademark by the Japanese game company Tsukuda Original. The name refers to Shakespeare’s play Othello, the Moor of Venice and the conflict between the Moor Othello and Iago. The object of the game is to control more spaces on the board than your opponent does.

Reversi board
Reversi board after first moves
Figure 1: Reversi board

Rules

The game is played on an 8 x 8 square board. There are 64 pieces, black on one side and white on the other.

Each player starts with 32 pieces. Initially the board is empty and black starts by placing one piece on any of the four center squares. White in turn places once piece on any of the three remainder center squares, followed by black and then white resulting in possible arrangements shown in Figure 1.

After multiple capture
Figure 3: After multiple capture
Before multiple capture
Figure 2: Before multiple capture

Next players in turn place one piece on the board at a time so that one or more of the opponent’s pieces are sandwiched between two of the player’s own pieces either orthogonally or diagonally. The sandwiched pieces are flipped over or reversed. A piece may be flipped over several times during a game.

A piece that is sandwiched when a captured piece is reversed is not itself captured. For example, when white plays at X in Figure 2, he captures along a both an orthogonal line and a diagonal line resulting in the situation in Figure 3. Although the black piece Y is now sandwiched is not captured.

A play is valid only if it captures one or more of the opponent’s men. If a player cannot make a valid move he loses his turn. When all 64 pieces are on the board, or when both players cannot make a valid move, the game is over and the player with the most pieces wins the game.