What it is
A go board you can actually play on: exact rules (captures, suicide, ko and positional superko, Chinese area or Japanese territory scoring, handicap, SGF), a Monte-Carlo tree search opponent with RAVE that thinks in a background worker, and a table that looks and sounds like the real thing — kaya grain, slate and shell stones with their own shadows, bowls, lids filling with prisoners, and the clack of a stone on wood. Plain HTML5 Canvas, Web Audio and vanilla JavaScript; no frameworks, no build.
Features
Exact rules
Zobrist-hashed positions for superko, simple ko, suicide, multi-group captures, two-pass ending, undo, handicap on the star points. 21 unit tests.
Monte-Carlo AI
UCT + RAVE with atari-aware playouts on a pseudo-liberty union-find board: ~32k playouts/s on 9×9. Three strengths, live win-rate, passes when ahead, resigns when lost.
Scoring phase
Dead stones suggested from playouts, click a group to flip it, score line updates live, accept or resume. Area or territory counting with komi.
Reading aids
Territory estimate overlay, move numbers, last-move ring, hover ghost stone, coordinates.
Table and sound
Photoreal board and stones with capture animations into the lids; synthesized clacks, clinks, pass and clock tones.
Clocks and records
Main time with byo-yomi periods and loss on time; SGF save and load.
Screenshots
Controls
| Action | Mouse | Keyboard |
|---|---|---|
| Play a stone | Click an intersection | — |
| Pass / Undo / Resign | Buttons | P / U |
| Estimate / Numbers / Coordinates | Buttons | E / N / C |
| Mark dead stones (scoring) | Click a group | — |
| New game / Mute | Buttons | G / M |
Run it yourself
Open index.html, or serve the folder (python -m http.server 8770 or start.cmd on Windows). The README covers the rules tests, self-play and the headless smoke test.