Backgammon Game

Classic checker movement on a 24-point board

Each side begins with fifteen checkers in the standard backgammon opening position. Your checkers travel from the 24-point toward the 1-point, then bear off from your home board. The computer travels in the opposite direction. Every displayed point number stays fixed, so a move label such as 13 → 8 means the same thing on mobile and desktop. The board view, legal-move buttons and independent rules engine all use the same point numbering.

The opening roll decides the first move

At the start of a game, each side receives one opening die. A tie is rerolled. The side with the higher number moves first and uses the two opening numbers as its first turn, which matches standard backgammon procedure. Later turns roll a normal pair. The seeded Practice and Daily modes make those rolls reproducible, so refreshing the same seed or reopening the same Daily date does not quietly replace the position with a different sequence.

Bar entry has absolute priority

A single checker on a point is a blot. If the opponent lands on that point, the blot is hit and placed on the bar. A player with one or more checkers on the bar must re-enter them into the opponent’s home board before moving any other checker. The legal-move generator applies this restriction before it considers ordinary moves. If every possible entry point for the available dice is closed, the unusable dice are handled by the same full-turn rules as any other blocked move.

Two opposing checkers close a point

An empty point is open. A point containing your own checkers is also open to you, and a point containing exactly one opposing checker can be hit. A point containing two or more opposing checkers is closed. The interface never offers a move onto a closed point. This is important because a backgammon turn is not just “move by one die, then see what happens”; the engine must understand how the first move changes what can be done with the remaining die.

The game enforces maximum legal dice use

When two different dice are rolled, you must use both if a legal sequence exists that uses both. If only one number can be played, the higher number must be used when it is legally available. Doubles provide four moves of the same value and the player must use as many of those four moves as the board permits. V0.96 generates complete legal turn sequences before exposing the first move, so a tempting move that unnecessarily wastes a usable die is not presented as legal.

Move order can change the whole turn

Suppose one die can open a path for the other, or one order becomes blocked while the reverse order uses both numbers. The engine explores both orders before deciding which first moves are valid. After you choose one legal first move, it repeats the process with the remaining dice from the new board state. This keeps the move buttons honest without asking the player to manually calculate every sequence before touching a checker.

Bearing off begins only when every checker is home

You may start bearing off only when all fifteen of your checkers are in your six-point home board and none is on the bar. An exact die removes a checker from its matching point. A larger die may remove a checker from a lower occupied point only when there is no checker farther from the exit. The same function handles exact and oversized bearing-off moves for both sides, and full-game property tests verify that each side always keeps exactly fifteen checkers across the board, bar and off tray.

Three computer levels use the visible board only

Backgammon has no hidden checker information, so the computer can evaluate the same public board you see. Easy chooses among legal full-turn sequences with a simple seeded choice. Standard values race distance, borne-off checkers, hits, made points and exposed blots. Hard weighs those features more carefully and prefers sequences that improve the position without violating any dice-use rule. Difficulty changes decision quality, not dice results or access to secret information.

Practice is deterministic instead of disposable

A Practice Game receives a seed that is fixed in the URL. The opening roll, later dice and computer decisions therefore remain reproducible. If a position is interesting, refreshing the page keeps the same game identity and autosave. Fresh intentionally creates another Practice seed. Race to 3 uses the same deterministic machinery but carries one match point for each completed game until either side reaches three.

Hint and Undo are study tools, not invisible advantages

Hint marks the current game Assisted and highlights one legal move selected by the strongest local evaluator. Undo turn rewinds to the beginning of your previous turn, including any computer response that followed it, and also marks the game Assisted because you have already seen information from the replayed sequence. Restart keeps the same deterministic game but changes the record to Assisted. Clean wins therefore mean the game was completed without those study actions.

Local autosave preserves the exact position

The browser-local save records the board, bar, borne-off checkers, current dice, turn, game index, match score and Clean or Assisted status. Reopening the same seed restores that exact state. V0.96 migrates forward from the previous versioned store while leaving the old serialized V0.84 value unchanged. No account or remote database is required for Practice, Daily history or specialist statistics.

No doubling cube or wagering system is included

This release treats backgammon strictly as a strategy board game. It does not include stakes, chips, prizes, purchases, a doubling-cube economy or any feature that simulates betting. Race to 3 is simply a local best-of-series score: each game is worth one match point. Keeping the product focused on checker play also makes the scoring and QA contract much easier to verify.

Daily Backgammon stays outside Today’s 6

The separate Daily mode maps a calendar date to one deterministic game and stores its own completion history and streak. It does not add Backgammon to the main six-game Daily rotation, does not write into the Today’s 6 day state and does not alter the frozen annual lineup sequence. Use Daily Backgammon when you want a repeatable specialist habit; use Practice when you want unlimited seeded games.