Doubling Cube
While everyone knows that two dice are used to play backgammon, every backgammon set contains three dice. The third die, known as the doubling cube is hardly ever used by casual players but serious backgammon aficionados know that it is an important part of their game strategy. By using the dice at the right time a player can make a contest winning move or a remarkable comeback. So just what is the doubling cube?
Most backgammon sessions and competitions are not just a single bout but rather are played over a series of games. Each game is worth one point and the player with the most points at the end of the series wins. In order to add an extra aspect to the tournament strategy and to speed up the play the doubling cube is used to double the value of points that the game is worth. In money games the doubling cube likewise doubles the stakes being played for. The cube is marked with increasing powers of two: 2, 4, 8, 16, 32, & 64, and at the start of the game is placed at a neutral point between the players. If one player feels that he or she has a significant advantage and is likely to win the game the player can 'double up' before taking a turn. This is done by turning the doubling cube to show the lowest value which is two. The opposing player must now choose to accept the challenge or resign and forfeit the game.
If the player accepts, the cube passes to that player and he or she now controls whether or not there is any further doubling. This means that the player who initiated the challenge cannot continue doubling the game at will and the right to double remains with the last accepting player. If the accepting player later feels that he has gained the advantage in the game he may then double the game again by turning the dice to show four, raising the point value of the game to four. Again the opposing player must decide to either accept or resign the game. Although the doubling cube only goes up to 64 points the cycle of doubling can continue to any value. In practice it is very rare for a game to be doubled more than four times.
In addition to the regular doubling there are additional rules commonly used. In money games in particular a player is often permitted to "beaver". This means that when offered the cube, the accepting player may immediately double again while still retaining control of the cube. Also some players use a an automatic double rule which means that if identical numbers show on the first throw of the game the stakes are automatically doubled. In this case however, the doubling cube remains at a neutral point between the players and neither player gains control of the cube.
Gregory Peters - Game Analyst
