Help For Backgammon
Welcome to the network Backgammon server.
The rules for Backgammon are below. The challenge and move commands for Backgammon are described here, as well as some special commands specifically for Backgammon: greedy, manual, roll, and double. Other commands are the same for all pbmserv games.
Backgammon Command Summary
Rules for Backgammon Introduction:
Backgammon is a game involving the skill of two players and the luck of two dice. There are two players, eks and ohs, and each player gets fifteen men. The object of the game is to re- move all your men from the board before the opponent does. The board consists of twenty-four positions, a 'bar' and a 'home' for each player. The initial board looks like this:
___________________________________________________ | | | | |13 14 15 16 17 18 | |19 20 21 22 23 24 | | O X | | X O | | O X | | X O | | O X | | X | | O | | X | | O | | X | | |BAR| |HOME | X | | O | | X | | O | | X O | | O | | X O | | O X | | X O | | O X | |12 11 10 9 8 7 | | 6 5 4 3 2 1 | |_______________________|___|_______________________|
A position may have zero or more pieces on it, e.g. position 12 has five eks pieces on it, while position 11 does not have any pieces of either color.
Moves and Points:
Moves are made along the positions on the board according to their numbers. eks moves in the positive direction (clockwise from 1 to 24), and ohs moves in the negative direction (coun- terclockwise from 24 to 1).
A turn consists of rolling the dice, and moving the number of positions indicated on each die. The two numbers can be used to move one man the sum of the two rolls, or two men the number on each individual die. For example, if eks rolled 6 3 at the start of the game, he might move a man from 1 to 7 to 10, using both dice for one man, or he might move two men from position 12, one to 15 and one to 18. (eks did not have to choose two men start- ing from the same position.) In addition, doubles are treated specially in backgammon. When a player rolls doubles, he gets to move as if he had four dice instead of two. For instance, if you rolled double 2's, you could move one man eight positions, four men two positions each, or any permutation in between.
However, there are certain limitations, called 'points.' A player has a point when he has two or more men on the same posi- tion. This gives him custody of that position, and his opponent cannot place his men there, even if passing through on the way to another position. When a player has six points in a row, it is called a 'wall,' since any of his opponent's men behind the wall cannot pass it and are trapped, at least for the moment. Notice that this could mean that a player could not use part or all of his roll. However, he must use as much of his roll as possible.
Removing Men from the Board:
The most important part of the game is removing men, since that is how you win the game. Once a man is removed, he stays off the board for the duration of the game. However, a player cannot remove men until all his men are on his 'inner table,' or the last six positions of the board (19-24 for eks, 6-1 for ohs).
To get off the board, a player must roll the exact number to get his man one position past the last position on the board, or his 'home.' Hence, if eks wanted to remove a man from position 23, he would have to roll a 2, anything else would be used for another man, or for another purpose. However, there is one ex- ception. If the player rolling has no men far enough to move the roll made, he may move his farthest man off the board. For exam- ple, if eks's farthest man back was on position 21, he could re- move men from that position if he rolled a 5 or a 6, as well as a 4. Since he does not have men on 20 (where he could use a 5) or on 19 (where he could use a 6), he can use these rolls for posi- tion 21. A player never has to remove men, but he must make as many moves as possible.
Although two men on a position form an impenetrable point, a lone man is not so secure. Such a man is called a 'blot' and has the potential of getting hit by an opposing man. When a player's blot is hit, he is placed on the bar, and the first thing that player must do is move the man off the bar. Such moves are counted as if the bar is one position behind the first position on the board. Thus if eks has a man on the bar and rolls 2 3, he must move the man on the bar to position 2 or 3 before moving any other man. If ohs had points on positions 2 and 3, then eks would forfeit his turn. Being on the bar is a very bad position, for often a player can lose many turns trying to move off the bar, as well as being set back the full distance of the board.
The Doubling Cube:
In backgammon, each game is worth one point. If you "double" your are telling your opponent "I am so confident that I'm going to win, I'm willing to double the value of the game". If you're playing for money, you've doubled the value of the stakes. If you're playing in a match (something that will be added eventually) you are attempting to make the game worth 2 (or more) points towards the end match condition.
The player who doubles, "Offers a double", does so before they roll their dice for that turn. The player who is "offered" the double has the option to accept the double, and play continues, or refusing the double,in which case the game is over, and the doubling player wins whatever value the doubling cube had *before* the double was offered.
However, currently the doubling cube has no effect on the pbmserv play. Your rating is changed using the same algorithm regardless of the state of the doubling cube.
Ending the Game and Scoring:
Winning a game usually wins one point, the normal value of a game. However, if the losing player has not removed any men yet, then the winning player wins double the game value, called a 'gammon.' If the losing player has a player on the bar or on the winner's inner table, then the winner gets triple the game value, which is called a 'backgammon.' (So that's where the name comes from!)
Some general hints when playing: Try not to leave men open unless absolutely necessary. Also, it is good to make as many points as possible. Often, two men from different positions can be brought together to form a new point. Although walls (six points in a row) are difficult to form, many points nestled close- ly together produce a formidable barrier. Also, while it is good to move back men forward, doing so lessens the opportunity for you to hit men. Finally, remember that once the two player's have passed each other on the board, there is no chance of either team being hit, so the game reduces to a race off the board. Addi- tional hints on strategy are presented in the practice game.