Backgammon is a two-player game, that involves a combination of strategy and luck, where each player has fifteen checkers or pieces that move between twenty-four triangles (points) according to the roll of two dice. The objective of the game is to be first to move all fifteen pieces off the game board. With each roll of the dice, players must choose from numerous options for moving their pieces and anticipate possible counter-moves by the opponent.
Setup and movement: The board consists of 24 long triangles called points or pips. The triangles alternate in color and are divided into four quadrants of six triangles each. The four quadrants are the player’s home board and outer board, and the opponent’s home board and outer board. The home boards and outer boards are separated by a divider down the middle referred to as the bar. The points form a continuous track in the shape of a horseshoe and the two players move their pieces in opposing directions as shown in the following image:
The image above also shows the starting positions of the checkers. The home board of the player with the white checkers is the top right quadrant, while the player with the black checkers has as home board the bottom right quadrant.
If a player rolls two of the same number, called doubles, that player must play each die twice. For example, a roll of 5-5 allows the player to make four moves of five spaces each. On any roll, a player must move according to the numbers on both dice if it is at all possible to do so. If one or both numbers do not allow a legal move, the player forfeits that portion of the roll, and the turn ends. If moves can be made according to either one die or the other, but not both, the higher number must be used. If one die is unable to be moved, but such a move is made possible by the moving of the other die, that move is compulsory.
Hitting a blot: In the course of a move, a checker may land on any point that is unoccupied or is occupied by one or more of the player's own checkers. It may also land on a point occupied by exactly one opposing checker, or "blot". In this case, the blot has been "hit" and is placed in the middle of the board on the bar that divides the two sides of the playing surface. A checker may never land on a point occupied by two or more opposing checkers (these points are called made points). Checkers placed on the bar must re-enter the game through the opponent's home board before any other move can be made.
Bearing off: When all of a player's checkers are in that player's home board, that player may start removing them (this is called "bearing off"). Since there are six points inside a player's home board, a checker placed on the deepest one, needs a roll of 1 to be bore off, on the second deepest needs a roll of 2 to be bore off, etc. If all of a player's checkers are on points lower than the number showing on a particular die, the player must use that die to bear off one checker from the highest occupied point. For example, if a player rolls a 6 and a 5, has no checkers on the 6-point but has two on the 5-point, then the 6 and the 5 must be used to bear off the two checkers from the 5-point. If a player's checker is hit while in the process of bearing off, that player may not bear off any others until it has been re-entered into the game and moved into the player's home board, according to the normal movement rules.