Game rules

Backgammon is a game played by two players. The game board has 24 narrow triangles called points. The points alternate in color and are grouped in four quadrants of six points each. The quadrants are called home board and outer board. The line that divides the home board from the outer board is called the bar.

All of the points are numbered. A players outermost point is called the 24-point, which also is the opponents 1-point. Each player has 15 checkers, and two dice are used to move them around the table. A doubling dice with the numbers 2, 4, 8, 16, 32, and 64 is used to keep track of the current stakes.

Each player rolls a dice to start the game. This roll both decides which player goes first and also is the first roll for that player. If both players roll the same number on the dice they roll again until one player rolls higher than the other and starts. The roll of the dice indicates how many points (or pips) a player can move his stones. After the first throw the players use both dice and alternate turns. The stones are always moved toward a point with a lower number. The following rules apply:

Hit and Enter

A point occupied by a single stone is called a blot. If one of the opponents stones land on the blot, it is hit and the stone is removed and placed upon the bar. Every time a player has one or more stones on the bar, he must get the stones back into his opponents home board. The stones enter the game again by being moved to an open point that corresponds to the dice number. For example, if a player rolls 4 or 6 he may enter into his opponent 4-point or 6-point (as long as the point is not previously occupied by two or more of the opponents stones). If no points are open the player forfeits his turn. If a player can enter with some of his stones but not all, he must enter with the stones he can. After the last of the players stone have entered, any unused numbers on the dice must be played.

Bearing off

As soon as a player has all their stones on their home board, they may start to remove their stones from the board, this is called bearing off. A player bears off from the points that correspond to the numbers of the dice. For example, if the player rolls 6 he may bear of a stone residing on that point. If there are no stone on the point that corresponds to the number of the dice, the player may remove a stone from a point with a higher number. If there are no stones on a point with a higher number, the player must remove a stone from the next point in the row. The player should not bear off if he can make a legal move. A player must have all their stones on their home board before bearing off. If a player is hit during bearing off, the player must move the stone that was hit to his home board before he can continue to bear off.

The Doubling Cube

Backgammon is played with a wager or point. Each game starts with 1 point. During the course of the game a player may double the point if he thinks he has enough advantage. The player can only do this before rolling the dice. The player who is offered the double may refuse it, in which case he concedes the game and pays the original wager. Otherwise, he must accept the double and play on for the new higher stakes. The doubling cube is then passed to the accepting player and only he can offer the next double. Subsequent doubles in the same game are called redoubles. If a player refuses a redouble he must pay the wager that was at stake prior to the redouble. If he accepts, the doubling cube is passed to him and the game continues with the new wager. Redoubles can increase the initial wager up to 64 times.

Gammon and Backgammon

If the loosing player in the end of the game has borne off at least 1 stone, he only looses the value shown on the doubling cube (one point if there are no doubles). If the loosing player has not borne off any stones it is called gammon and he loses twice the value of the doubling cube. If the loosing player has yet to move all of his stones to his home board and there still is a stone on the bar or the opponents home board, it is called backgammon and he loses three times the value of the doubling cube.

Jacoby rule

With the Jacoby rule, gammon and backgammon can only be achieved if one of the players has offered to double during the course of the game. This encourages a player with a big lead to double, and most likely end the game instead of seeing it to the end in the hopes for a gammon or backgammon. The jacoby rule is often used in cash games, but not in match play..

Beavers

An optional rule in single game mode. When a player is doubled, he can make a redouble and keep the doubling cube. The player who made the initial double may accept or refuse just as with a normal doubling.

Crawford rule

The Crawford rule makes the game more fair for the leading player. If a player is 1 point away from winning his opponent has no reason not to double; a win by the player in the lead is still a win no matter what the doubling stakes are at the moment, while on the other hand a win for his opponent is worth twice as much if the wager is doubled. Thus, there is no advantage towards winning the match to being one point shy of winning, if one's opponent is two points shy.

The Crawford rule says that no player may use the doubling cube when a player is 1 point away from winning the match. A game that uses this rule is called a Crawford game, but when it is over all further games can use the doubling cube as normal. This rule is not quite as common as the Jacoby rule, but is often used and generally presumed to be in play at match games.

Automatic doubles

When automatic doubles are being used all rerolls by a player in the beginning of the game(when both players roll 1 dice) causes a double. For example, if you get 3 3 and roll 5-5 and then 1 -4, the game will start with 4 times the normal wager. The doubling cube stays in the middle where both players can reach it. The Jacoby Rule is also in effect.

Automatic doubles are common in money games (after agreement). They are never used in match games. A known variant of this rule is 6-6 trippling, instead of doubling, the wagers.