Seems straightforward? Yes indeed, but this simple system is spiced up by the addition of the doubling cube which brings an exciting gambling element to the game.

The doubling cube:
The doubling cube is used to raise the stakes in an individual game. The stakes may be points or a sum of money, depending on the type of game being played.

The doubling cube looks like a large dice but with the numbers 2, 4, 8, 16, 32 and 64 on its faces. It is initially placed in the middle of the bar with the 64 face up, though its actual value at the beginning of the game is 1 (there is no 1 face). As long as it stays in this position the stakes remain at their original level.

If you reach a position in the game where you feel confident of winning, on your turn and before you roll the game dice, you can choose to turn the doubling cube to 2 to announce a double. This challenges your opponent to double the stakes of the game. The other player must now make a decision: either accept the double and continue the game at a twice the stakes, or refuse the double and concede the game for its current value.

If your opponent accepts the double they take control over the cube. The option to use the cube now rests with them. If at some point they feel that the game has turned in their favour they can redouble, turning the cube to 4. The decision is now yours as to whether you will accept the redouble and take over the cube, or concede the game.

Control of the doubling cube is passed between the players in this way with each given the option to redouble at any time before they roll the dice.

So the stakes increase 1-2-4-8-16-32-64 with each use of the cube. If it is at, say, 16 then the stakes are now at 16 times the original value. The doubling cube is really just used to keep track of the enhanced value of the stake. (Incidentally, whilst it is customary to use a doubling cube, in actual fact the process of doubling can occur without one. If a cube is not available you can just keep a written record of the stake value.)

If a player declines a double or a redouble they concede the game immediately and must pay winnings to the other player at the last doubling value that was accepted.

The importance of the doubling cube is particularly apparent if you get a gammon or backgammon:

• If you bear off all of your checkers before the other player has borne off any of theirs, you have 'gammoned' your opponent. Ordinarily a gammon is worth 2 points (or double money). If a doubling cube is in use, the game is thus worth twice the value of the doubling cube. So, for example if you are playing $10 per point and the doubling cube is set at 8, you win $10 x 2 x 8 = $160.
• If you bear off all your checkers before the other player has borne off any of theirs, and while they have at least one checker left in your home board or on the bar, you have 'backgammoned' your opponent. Ordinarily a backgammon is worth 3 points, or triple money. With the doubling cube in use the game is worth three times the value of the doubling cube. So in the example above a backgammon would win you the grand total of $10 x 3 x 8 = $240.

The Beaver Rule - and other animals!
The Beaver rule may often be used in money games, though not in match-play or tournaments.

Normally, when a player announces a double they lose control of the doubling cube. If the Beaver rule is being played, the player to whom the double has been offered can opt to immediately announce a redouble and still maintain control of the cube. This is called a 'beaver'.

In some circumstances the players may agree to other animals being allowed in the game! This works as follows:

• Player One believes he has the upper hand and doubles
• Player Two feels this confidence is misplaced and immediately says 'Beaver!' and redoubles, turning the cube to 4
• Player One is adamant of their superiority and redoubles again, calling 'Raccoon!' and moving the cube to 8.
• Player Two could if he likes turn the cube again, naming some other creature.

The Crawford rule
The Crawford rule is another option which can be brought into a game. This states that if either player is just one point away from winning the match, the next game is played without the doubling cube. If the match is still not over after that game the doubling cube comes back in use.
The reason for this rule is that the weaker player is inclined to simply double and redouble because they have nothing to lose. They are seen as having an unfair opportunity to use the doubling cube to snatch victory against the run of play.

The Jacoby rule
This optional rule is used only in money games. It states that a backgammon or gammon may not be scored as such once the doubling cube is in play. This is to avoid the possibility of one player taking a huge number of points in one game and skewing the match to an excessive degree.

Mai Shen is a writer and researcher on The Backgammon Guide, which provides online Backgammon information and resources, including reviews of online backgammon games, backgammon tips, backgammon shopping & gifts and more. Use of this article is permitted as long as there are clickable links back to us at The Backgammon Guide (http://www.the-backgammon-guide.com/) and credit is given to the author.