Your opponent offers the cube at 2.
Dropping concedes the game at the stake before this double.
1
White wins a single game.
2 – 1
Every rule below is taken from a published source and is followed exactly. Where sources genuinely differ, the difference is named and the choice is stated.
24 triangles called points, in four quadrants of six, split by the raised bar. Each player numbers them from their own home board outward, so your 24-point is your opponent's 1-point. Points 1 to 6 are your home board; the 7-point is the bar point, the 13 the midpoint, the 5 the golden point. Checkers always move to a lower-numbered point.
15 checkers a side: 2 on the 24-point, 5 on the 13, 3 on the 8 and 5 on the 6. That is a 167-pip journey for each of you.
Each player throws one die; the higher number goes first and plays both numbers as they lie. Equal numbers are thrown again, so the opening turn is never doubles.
A checker may move only to an open point: one that does not hold two or more of your opponent's checkers. The two dice are separate moves and one checker may play both, provided the point it touches down on is open too. Doubles are played 4 times.
You must use both numbers if there is any legal way to do it — and that is a property of the whole turn, not of either move on its own. If only one number can be played you must play it; if either can be played but not both, you must play the larger, even when the smaller one would hit. If neither can be played you forfeit the turn. With doubles you must play as many of the four as you can. This board will simply not offer you a move that strands a die.
You may undo and replay as often as you like until you end the turn — the turn is over only when you pick the dice up.
A checker alone on a point is a blot. Landing on it sends it to the bar, and its owner must bring it back into your home board before moving anything else. A roll of n enters on your opponent's n-point. If neither number gives an open point you lose the turn; if all six of the opponent's home points are made, you are closed out and cannot move at all. Hit-and-run is allowed, including in your own home board.
All 15 checkers must be home first, and a checker hit during the bear-off has to come all the way round again. An exact roll bears a checker off its own point. If that point is empty you must move a checker from a higher one — and only when there is nothing higher at all may (and must) a die take a checker off your highest occupied point. You may always play the numbers in either order, and you are never obliged to bear off when some other legal move exists.
The first side to bear off all fifteen wins. If the loser has borne off at least one checker it is a single game. If the loser has borne off none it is a gammon, worth 2 times the cube. If the loser has borne off none and still has a checker on the bar or in the winner's home board it is a backgammon, worth 3 times.
The cube shows 2, 4, 8, 16, 32, 64 and starts centred, "on 1". Either player may double at the start of their own turn, before rolling. The opponent takes — and then owns the cube, so only they may redouble — or drops and concedes the stake as it stood before the double. There is no limit on redoubles.
Crawford (match play, always on): for the first game after either player comes within one point of the match, the cube is out of play. A cube is also dead for a player who would already win the match by winning at the current level.
Jacoby, beavers and automatic doubles are money-play options and are offered only there, because they are not used in match play. They are all off by default.
The pip count is how far your checkers still have to travel; a checker on the bar counts 25. A blot 17 rolls out of 36 hit a blot six pips away — the most dangerous distance on the board — against 11 at one pip.
Backgammon is not anyone's property. It is a game of the tables family, played in something close to this form for centuries; the doubling cube was added in the 1920s, and since 2018 the international rules have been set by the World Backgammon Federation. This is an independent implementation of those public rules. No code, artwork or data from any other backgammon program was used, and none was examined.
Completely, on the rules — and that is the point of this build. Every rule of play here cites a published source, and the hard ones are not merely asserted, they are proved:
The numbers come from a seeded pseudo-random generator in the rules engine. The tumble you see is then staged to land showing the number that has already been drawn. The physics does not decide anything — there is no physics. Every game is reproducible from its seed, and the harness checks that the faces on the table always equal the roll the engine made.
The board's proportions, colours and camera; the checker and die shapes; the tumble timing; the opponent's evaluation weights and its estimate of who is winning; and the shape of the interface. None of these is a rule, and none is claimed to be canonical. The rules themselves contain nothing reconstructed.
It costs nothing, needs no account, calls no model and sends nothing anywhere. Your settings and your record live in this browser's own storage, and Options can clear them.
CREDITS.txt in this bundle carries the full list with URLs, and marks every value as documented or the author's own.
Seed of this game: -