Official Backgammon Rules
Setup:
Bookgammon™ is backgammon in a book safe and therefore follows traditional backgammon rules. It’s a game for two players. There is a ‘board’ in the book consisting of 24 narrow triangles, called points or pips. The triangles alternate in color and/or image and are grouped into four quadrants of six triangles each. We refer to the quadrants as the player’s and opponent’s home boards and outer boards. The binding acts as a ridge down the center of the board, separating the home and outer boards. The official backgammon rules call it a bar, so let’s make it a drinking game. Cheers!
Figure 1. A board with checkers in their initial position. An alternate arrangement is the reverse of the one shown here, with the home board on the left and the outer board on the right.
The points are numbered for either player starting in that player’s home board. The outermost point is the twenty-four point, which is also the opponent’s one point. Each player has fifteen checkers of his own color.
Both players have their own pair of dice. A doubling cube, with the numerals 2, 4, 8, 16, 32, and 64 is used to keep track of the current stake of the game. (GAMBLING! see Doubling below)
Object:
The object of the game is to move all your checkers into your own home board and then ‘bear’ them off (see below). The first player to bear off all of their checkers wins.
Figure 2. Direction of movement of White’s checkers. Red’s checkers move in the opposite direction.
Movement:
To start the game, each player throws a single die. This determines both the player to go first and the numbers to be played. If equal numbers come up, both players roll again until they roll different numbers. The player throwing the higher number moves their checkers according to the numbers rolled. After the first roll, two dice are thrown and turns alternate.
The roll of the dice indicates how many points, pips, or triangles the checkers are moved. They’re always moved forward and to a lower-numbered point. The following rules apply:
A checker may be moved only to a point they already occupy or an open point, one that is not occupied by TWO or more opposing checkers.
The numbers on each die constitutes a separate move. For example, if a player rolls a 5 and 3, one checker moves five spaces and another checker three spaces. Or one checker moves a total of eight spaces, but only if the intermediate point (either three or five spaces from the starting point) is open or one they occupy.
Figure 3. Two ways that White can play a roll of 
.
Players rolling doubles play the numbers shown on the dice twice. A roll of 6 and 6 means that the player has FOUR sixes to use!
A player MUST use both numbers of a roll if legally possible to do so (or all four numbers of a double).
When only one number can be played, the player must play that number. Or if either number can be played but not both, the player must play the larger one. When neither number can be played, the player loses their turn. In the case of doubles, when all four numbers cannot be played, the player plays as many numbers as they can.
Hitting and Entering:
A point occupied by a single checker of either color is called a blot. If an opposing checker lands on a blot, the blot is considered hit and placed on the bar. Everybody drink. Any time a player has one or more checkers on the bar, their first obligation after drinking is to enter those checkers into the opposing home board. A checker is entered by moving it to an open point corresponding to one of the numbers on the rolled dice.
For example, if a player rolls 4 and 6, they enter a checker onto either the opponent’s four point or six point, as long as the prospective point isn’t occupied by two or more of the opponent’s checkers.
Figure 4. If White rolls with a checker on the bar, they must enter the checker onto Red’s four point since Red’s six point is not open.
If neither of the points is open, the player loses their turn, however, if they’re able to enter some but not all of their checkers, they enter as many as they can and then forfeit the remainder of their turn.
After the last of a player’s checkers has been entered, any unused numbers on the dice are played by moving either the checker that was entered or a different checker.
Bearing Off:
Once a player moves all fifteen checkers into their home board, they commence bearing off. Might as well drink to celebrate! Checkers are beared off by rolling a number that corresponds to the point on which the checker resides, then removing that checker from the board. So, rolling a 6 permits the player to remove a checker from the six point.
If there is no checker on the point indicated by the roll, a legal move must be made using a checker on a higher-numbered point. If there are no checkers on higher-numbered points, a checker must be removed from the highest point on which one resides. There’s no obligation to bear off if an otherwise legal move can be made.
Figure 5. White rolls and bears off two checkers.
All checkers have to be in their home board in order to bear off. If a checker is hit during the bear-off process, the player brings that checker back to their home board before continuing to bear off. The first player bearing off all fifteen checkers wins the game. Drink!
Doubling:
Bookgammon is played for an agreed stake per point. Each game starts at one point. During the course of the game, a player who feels they have a sufficient advantage may propose doubling the stakes. They can only do this at the start of their own turn and before they’ve rolled the dice.
A player can refuse a doubling offer, in which case they concede the game and pay one point. Otherwise, they accept the double and play on for the new higher stakes. A player accepting a double becomes the owner of the cube and only they can make the next double.
Subsequent doubles in the same game are called redoubles. If a redouble is refused, the player pays the number of points that were at stake prior to the redouble. Otherwise, they become the new owner of the cube and the game continues at twice the previous stakes. There is no limit to the number of redoubles in a game.
Gammons and Backgammons:
At the end of the game, if the losing player bears off at least one checker, they lose the value on the doubling cube (one point, if there have been no doubles). However, if the loser doesn’t bear off any of their checkers, they’re gammoned! They lose TWICE the value of the doubling cube! Or worse, if the loser doesn’t bear off any checkers AND still has a checker on the bar or in the winner’s home board, they’re backgammoned! They lose THREE TIMES the value of the doubling cube! If you were playing for drinks, and we hope you were, you might want to get a ride home.
*Backgammon rules compliments of www.bkgm.com