Reversi (Othello) — Rules
VOG — Vinco Online Games
Reversi (Othello)
Reversi, also known as Othello, is a strategy game played by two players: Black and White. It is played on an 8x8 board (usually green in colour), called the Othello board. The two players place 64 discs, each of which is black on one side and white on the other. For convenience, each player begins with 32 discs but these do not belong to him and if his opponent runs out of discs, he is obliged to give him some. A disc is black if the black side is visible and white if the white face is on top.
The Goal of the Game
The winner is the player who has more discs of his colour than his opponent at the end of the game. This will happen when neither of the two players has a legal move. Generally at this stage all 64 squares are occupied.
Starting Position
Fig. 1: The Initial Position
At the beginning of the game, two black discs are placed on e4 and d5 and two white discs on d4 and e5 (see fig. 1).
Black always begins, and the two players subsequently take turns moving.
Making a Move
Fig. 2: Black plays f5...
Fig. 3: ...and flips e5!
Fig. 4: White can play f4, f6 or d6
Fig. 5: If White plays d6...
At his turn, a player must place a disc of his colour on one of the empty squares of the Othello board, adjacent to an opponent's disc. In addition, by placing his disc, he must flank one or several of his opponent's discs between the disc played and another disc of his own colour already on the board. He then flips to his colour all the discs which were flanked. The discs are neither removed from the Othello board nor moved from one square to another.
Black's first move may be, for example, to f5 (see fig. 2). By playing f5, he flanks the white disc at e5 between the disc played and another black disc already on the board (here d5); he then flips this disc (see fig. 3). Black could also have moved to e6, c4 or d3. However, these four black moves are perfectly symmetrical; Black needn't spend time thinking about his first move.
Now it's White's turn to move. He has three possible moves (see fig. 4). Each possible move flips at least one opponent's disc. White may play f4, f6 or d6. Note that discs can be flanked in all eight directions. Furthermore, in each direction several discs may be flanked (see fig. 6 and 7). All these flanked discs must be flipped.
Fig. 6: Black plays c6...
Fig. 7: ...resulting in this position.
Black has played to c6. He turns the discs at b6 (flanked by the disc at a6), b5 (flanked by a4), d7 (flanked by e8), c5 and c4 (flanked by c3). Note that neither d6 nor e6 are flipped due to the empty square at f6.
Fig. 8: Black plays a5...
Fig. 9: ...the disc on c4 remains White.
Flipped discs cannot cause further flips in the same move. This is shown in fig. 8 where Black plays a5:
The discs on b5 and c5 are flipped, but the white disc on c4 is not flipped because one of the surrounding discs only became black as a result of this same move (fig. 9).
If it is your turn to move but you cannot make a legal move that flips at least one of your opponent's discs, you pass. But if a move is available, you must make it.
End of Game
Fig. 10: Game over!
The game is over when neither of the two players can make a move.
Generally this happens when all 64 squares are filled. However, it is possible that some empty squares remain which neither player can play: for example, if all the discs on the board are the same colour, or in a position like fig. 10.
Neither player can play b1, since doing so would not flank any opponent's discs. In this case, the discs are counted to determine the final score. Empty squares are given to the winner. In this game White has 29 discs and Black has 34. The empty square also counts for Black. Thus Black wins 35-29.