Reversi is a
board game for two players that was invented in
England at the end of the
19th century. It has become more popular recently since it was marketed under the name '
Othello'. Othello is the same as Reversi apart from that only the diagonal starting formation is allowed, and Black starts.
Reversi boards have an 8 by 8 grid marked on them and are usually dark green. There are 64 identical playing pieces, which are black on one side and white on the other side.
The two players are known as White and Black. White starts by placing a piece, own colour facing upwards, in one of the four centre squares. Black does the same, and this process is repeated once more. The board is now in one of these two basic formations
8........ 8........
7........ 7........
6........ 6........
5...bw... 5...ww...
4...wb... 4...bb...
3........ 3........
2........ 2........
1........ 1........
abcdefgh abcdefgh
(Diagonal) (Straight)
Once this is completed, normal play starts. Players take it in turns to place a piece, own colour upwards. At least one piece must be captured on each turn.
A piece is captured if is sandwiched between two discs of the opposing colour, either
orthogonally or
diagonally. Captured pieces turned over so that their colour is
reversed. A simple capture is shown in the diagram below. Black plays at d6. The white piece on d5 is sandwiched between d6 and d4, so it is captured.
8........
7........
6...*....
5...wb...
4...bw...
3........
2........
1........
abcdefgh
More complicated captures are also allowed. More than one piece can be captured along any particular line, and captures in multiple directions allowed. An example is shown in the diagram below: Black plays at e6, capturing d6, d5, e5 and e4.
8........
7........
6..bw*...
5...ww...
4..bww...
3..wbb...
2........
1........
abcdefgh
Note that only the currently played piece determines capturing. If a player cannot make a valid capture, then play passes to the opponent.
Play continues in this way until all 64 squares have been occupied, or until neither player can make a valid capture. The winner is the person who has more pieces with his colour facing upwards.
Despite its simple rules, Reversi contains some very deep strategy. As a general rule, do not be too hasty to capture as many pieces as possible in the early game: having too many pieces at this stage makes it too easy for your opponent to make big multiple captures.
Corners are critical in Reversi since once occupied they cannot be captured by the other player. Consequently, the squares which allow your opponent to place a piece in a corner (e.g. b1, b2, a2), should be avoided unless absolutely necessary. See also the node on
Reversi Strategy.