Go Game

Every stone uses the same liberty engine

The board is not a decorative grid with a few hand-written capture cases. Each orthogonally connected group is discovered from the current board, and every group carries the set of empty neighboring points that form its liberties. After a stone is placed, adjacent opposing groups with zero liberties are removed. The new player group is then checked in the updated position, so a move that looked suicidal can still be legal when it captures first.

Suicide is rejected after captures are resolved

A placement is illegal when the new stone’s connected group has no liberty after any opposing captures have been removed. That order matters. A move into a surrounded point can be legal if it removes the surrounding group, while a visually similar move can be illegal when nothing is captured. The interface asks the exact rules engine instead of guessing from the local neighborhood.

Positional superko stops board repetition

Go can create capture loops in which players would otherwise repeat the same position. This implementation keeps a browser-local history of board keys and rejects a stone placement that recreates any earlier board position in the game. Passes remain legal because they do not place a stone. The rule is deliberately described as positional superko rather than pretending every Go ruleset uses the same repetition wording.

Two passes end the game

A pass gives the move to the other color without changing the board. Two consecutive passes finish the current game and trigger scoring. Any normal stone move resets the consecutive-pass count. The status area always shows whether one pass is currently on the board so you can tell when a second pass would immediately score the position.

Area scoring is transparent about the board as played

At the end, Black receives one point for every black stone plus every empty point connected only to Black. White receives the same area count plus 6.5 komi. The browser does not ask a remote server or human referee to decide which remaining groups are dead. That means unsettled groups should be played out before both sides pass. The final result shows Black’s exact area score, White’s score including komi and the winning margin.

9×9 is the quickest way into real Go decisions

The smaller board still teaches liberties, connecting, cutting, capturing races, influence and territory, but it reaches consequential fights much faster than 19×19. That makes it practical on a phone and suitable for a daily habit. Daily Go therefore stays fixed at 9×9 so every date has the same board-size contract.

13×13 gives practice more room

Practice can switch to 13×13 when you want a longer game with more separation between local fights. The larger board gives opening direction and whole-board balance more room to matter while remaining responsive for a browser-local heuristic opponent. The product does not claim that its local AI is a professional-strength 19×19 engine.

Easy, Standard and Hard share exactly the same legal moves

Difficulty changes only how the browser chooses among legal moves. Easy uses deterministic seeded variation. Standard gives more weight to captures, liberties, connection and atari pressure. Hard chooses the strongest result under a stricter version of the same auditable local heuristic. None of the levels receives hidden information, a remote engine or different rules.

Practice sessions are reproducible

Opening Practice without a seed writes a generated seed into the URL. That seed stabilizes seeded-random color selection and AI tie breaks, while your own choices still determine the game. Refresh or same-seed reopen returns to the saved session rather than silently replacing it. Fresh Practice intentionally creates another seed.

Hint and Undo are study tools with a visible boundary

Hint asks the strongest local heuristic for one legal point and marks that intersection. Undo restores the position from immediately before your previous move, including the computer reply that followed. Both actions mark the game Assisted because they reveal or revisit information. Restart keeps the same deterministic setup and also marks the new attempt Assisted.

Clean wins do not pretend to be a rank

A Clean win means only that you finished without Hint, Undo or Restart. It is not an Elo rating, kyu rank, global percentile or comparison against other players. Local games, wins, Clean wins, best winning margin and Match-to-3 results describe only this browser’s own history.

Daily Go stays outside Today’s 6

The specialist Daily maps the date to a stable seed and player color, stores its own completion history and streak, and never writes a Go result into the frozen main `days` rotation. That separation allows the Practice catalog to grow without silently changing the established Today’s 6 product.