Koa Backgammon

The goal

Bring all fifteen of your checkers into your home board (points 1 to 6, bottom right) and then bear them off. The first player to bear off all fifteen wins.

Moving

Roll two dice. Each die is a separate move: with a 5 and a 2 you move one checker 5 points and another 2, or one checker 7 (if it can stop on the way). A double is played four times.

You must use both dice if you can. If only one can be used, use the larger one when possible.

Where you can land

A checker can land on an empty point, a point with your own checkers, or a point with one opposing checker. A point with two or more opposing checkers is blocked.

Hitting and the bar

A single checker on a point is a blot. Land on an opposing blot and it goes to the bar in the middle. A checker on the bar must come back in through the opponent's home board (your points 24 to 19) before anything else moves. If every entry point is blocked, the turn is lost.

Bearing off

Once all fifteen of your checkers are home, take them off with the number rolled: a 4 takes a checker off your 4-point. A bigger number takes one off your highest point when nothing sits higher.

Winning

A normal win is worth 1 point. If the loser hasn't borne off any checkers, it's a gammon (2 points). If they also still have a checker on the bar or in your home board, a backgammon (3 points).

The doubling cube

Before rolling, you may double the stakes. Your opponent either takes (plays on for twice as much and keeps the cube, so only they can double next) or drops (gives up the game at the current value).

A match is played to a number of points. In the game right after someone gets within one point of winning the match, nobody may double (the Crawford rule).

Playing here

• Tap a checker with a gold rim, then tap where it goes (shown in gold). If it has only one place to go, one tap moves it.
• Undo takes a step back; Done ends your turn.
• The pip count beside each name is how far that player still has to travel. Lower is better in a race.
• In Training, the coach rates each move and shows a better one. Stuck? Press Hint.
• After a game, Review this game lists your mistakes with the better play, and how well you played overall.
• Keyboard: Space or Enter rolls and finishes a turn, Backspace undoes.

About the coach

On the website, the coach uses GNU Backgammon, one of the strongest backgammon programs, running in your browser. It's free software under the GNU General Public License v3; its source code is at ftp.gnu.org/gnu/gnubg. In the offline file the coach uses the game's own, simpler engine.

Three tips to start

• Make points in your home board, especially your 5-point and 4-point. They block your opponent.
• Avoid leaving blots where your opponent's checkers can reach them.
• Ahead in the race? Play safe and run. Behind? Keep a couple of checkers back to hit later.