Backgammon

Backgammon Rules

Backgammon is for 2 opponent, played on a board be made up of 24 narrow triangles pieces called points. There is 2 color for The triangles and each color is belong to each player. The triangles alternate in color and are grouped into four quadrants of 6 triangles each. The quadrants are referred to as a player's home board and outer board, and the opponent's home board and outer board. The home and outer boards are set apart from each other by a thin ridge in the center of the board called the bar.

Both players have their own pair of dice and a dice cup used for shaking. A doubling cube, with the numerals 2, 4, 8, 16, 32, and 64 on its faces, is used to keep track of the current stake of the Backgammon game.

The rules of backgammon are of moderate complexity and can usually be learned quickly. In short, a player tries to get all of his own checkers past those of his opponent and then remove them from the board. The pieces are scattered at first and may be blocked or captured by the opponent.

Because the playing time for each individual game is short, it is often played in matches, where, for example, victory is awarded to the player who first wins five points.

Setup

Each side of the board has a track of twelve adjacent spaces, called points, usually represented by long triangles of alternating color. The points are considered to be connected across one edge of the board, forming a continuous track analogous to a horseshoe (but not a circle). The points are numbered from 1 to 24, with checkers always moving from higher-numbered points to lower-numbered points. The two players move their checkers in opposite directions, so the 1-point for one player is noted as the 24-point for the other. Some recorded games, however, keep the numbering of the points constant from the perspective of one player. Each player begins with two checkers on his 24-point, three checkers on his 8-point, and five checkers each on his 13-point and his 6-point.


Path of movement for blue and green; checkers are in starting positionPoints 1 to 6 are called the home board or inner board. A player may not remove any of his checkers until all 15 have reached his home board. Points 7 to 12 are called the outer board, points 13 to 18 are the opponent's outer board, and points 19 to 24 are the opponent's home board. The 7-point is often referred to as the bar point and the 13-point as the mid point.


Movement
At the start of the game, each player rolls one die. Whoever has rolled a higher number moves first, using the numbers on the two dice already rolled. In the case of a tie, both players roll again. The players then alternate turns, rolling two dice at the beginning of each turn.

After rolling the dice a player must, if possible, move checkers according to the number of points showing on each die. For example, if he rolls a 6 and a 3 (noted as "6-3") he must move one checker six points forward, and another checker three points forward. The dice may be played in either order. The same checker may be moved twice as long as the two moves are distinct: six and then three, or three and then six, but not all nine at once.

A checker may land on any point that is either unoccupied or is occupied only by a player's own checkers. It may also land on a point occupied by exactly one opposing checker; such a lone piece is called a blot. In the latter case, the blot has been hit, and is placed in the middle of the board on the bar, the divider between the home boards and the outer boards. A checker may never land on a point occupied by two or more enemy checkers, thus, no point is ever occupied by checkers from both players at the same time.

If a player has no legal moves after rolling the dice, because all of the points to which he might move are occupied by two or more opposing checkers, he must forfeit his turn. However, a player must play both dice if it is possible. If he has a legal move for one die only, he must make that move and then forfeit the use of the other die. If he has a legal move for either die, but not both, he must play the higher number.


Medieval players, from the 14th century Codex ManesseIf a player rolls two of the same number (doubles) he must play each die twice. For example, upon rolling a 5-5 he must move four checkers forward five spaces each. As before, a checker may be moved multiple times as long as the moves are distinct.

Checkers placed on the bar re-enter the game through the opponent's home field. A roll of 2 allows the checker to enter on the 23-point, a roll of 3 on the 22-point, etc. A player may not move any other checkers until all of his checkers on the bar have first re-entered the opponent's home field.

When all of a player's checkers are in his home board, he must bear off, removing the checkers from the board. A roll of 1 may be used to bear off a checker from the 1-point, a 2 from the 2-point, etc. A die may not be used to bear off checkers from a lower point unless there are no checkers on any higher points. A checker borne off from a lower point than indicated on the die still counts as a move for the full value of the die. For example, a 4 may be used to bear off a checker from the 3-point only if there are no checkers on the 4-, 5-, or 6-point.

If one player has not borne off any checkers by the time his opponent has borne off all fifteen, he has lost a gammon, which counts for double a normal loss (that is, two games toward the match in a game with normal stakes). If a player has not borne off any checkers, and still has checkers on the bar, or in his opponent's home board by the time his opponent has borne off all fifteen, or both, he has lost a backgammon, which counts for triple a normal loss (that is, three games toward the match in a game with normal stakes). In some variants, a further distinction is made between pieces in the opponent's home board, counting as a triple loss, and pieces on the bar, for a quadruple loss.


Doubling cube

Backgammon set, 19th centuryTo speed up match play and to increase the intensity of play and the need for strategy, a doubling cube is normally used. The doubling cube is a 6-sided die that, instead of the numbers 1–6, is labeled with 2, 4, 8, 16, 32 and 64. If a player believes his position to be superior he may, before rolling the dice on his turn, double, demanding that the game be played for twice the current stakes. The doubling cube is then placed with the 2 side face up to show that the game's value has been doubled. His opponent must either accept the challenge or resign the game on the spot. Thereafter the right to redouble (double again) belongs exclusively to the player who last accepted a double. When this occurs, the cube is placed with the face of the next power of two showing.

The game is rarely redoubled beyond four times the original stake, but there is no theoretical limit on the number of doubles. Although 64 is the highest number depicted on the doubling cube, the stakes may rise to 128, 256, 512 and so on.

A common rule allows a player to beaver, that is, to immediately redouble when offered the doubling cube. The redouble must be called before the player who initially doubled rolls the dice. The cube remains in the control of the player who offers the beaver. In this way, the stakes of the game can rise rapidly. A raccoon is sometimes pemitted as a response to a beaver. A player who accepts a beaver may offer a raccoon, redoubling again. Beavers and raccoons are commonly allowed when backgammon is played for money game by game and usually not allowed in matches.

The Jacoby rule allows gammons and backgammons to count for their respective double and triple values only if there has been at least one use of the doubling cube in the game. This encourages a player with a large lead in a game to double, possibly ending the game, rather than to see the game out to its conclusion in hopes of a gammon or backgammon. The Jacoby Rule is widely used in money play but is not used in match play.

The Crawford rule is designed to make match play more equitable for the player in the lead. If a player is one point away from winning a match, his opponent has no incentive not to double; whether the game is worth one point or two, the outcome of the match is unaffected. To balance the situation, the Crawford rule requires that when a player first reaches a score one point short of winning the match, neither player may use the doubling cube for the following, called the Crawford game. After the Crawford game, normal use of the doubling cube resumes. The Crawford rule is normally used in most match play.

Sometimes automatic doubles are used, meaning that any ties in the very first roll of the game automatically double the stakes. Thus, after a 3-3 roll, followed by a re-roll of 5-5, followed by a re-roll of 1-4 to begin the game itself, the game would be played for quadruple stakes. The doubling remains in the middle, with both players having access to it, and the Jacoby Rule is still in effect. Again, automatic doubles are common in money games. but they are rarely, if ever, used in match play.