Go is a two-player abstract strategy game played on a 19×19 grid (with smaller 9×9 and 13×13 variants for shorter games). Each player places stones to surround territory and capture enemy groups. Despite simple rules, Go has more legal positions than atoms in the observable universe — it's widely considered the deepest abstract strategy game ever invented.
Black plays first, then players alternate placing one stone of their color on any empty intersection. A stone or group with no adjacent empty points (no liberties) is captured. This version uses area scoring: your stones on the board plus the empty points they surround. Captured stones are not added separately. Komi (a points adjustment) compensates White for going second.
Both are abstract strategy with perfect information, but Go favors positional accumulation over tactical exchange. The game tree is far larger; computer mastery only arrived in 2016 with AlphaGo.
You may not immediately recapture a single stone in a way that recreates the previous board position. Prevents infinite capture loops. Larger ko fights are central to high-level strategy.
9×9 — completes in 10–15 minutes and reveals territory and capture concepts cleanly. Move to 13×13 once captures feel natural, 19×19 for full-board strategy.
A points compensation given to White (the second player) at the end. Modern komi is 6.5 or 7.5, fractional to prevent draws.
Two passes in a row open a marking step. Click any group to mark it dead; the whole group toggles together and the score updates straight away, with dead stones treated as empty points for the side that surrounds them. Confirm locks in the final score. Resume Play restores the position exactly as it was before the passes, gives the move to the correct player and needs two new passes before scoring again.
The computer looks one move ahead. It tries every legal point, gives each a score and then picks at random among the moves within 2 points of the best, so it does not repeat the same game. The score rewards capturing (20 per stone), rescuing its own group from atari, and putting your groups in atari. It penalises moves that leave its own group in atari, and strongly penalises filling one of its own eyes. Smaller bonuses go to touching its own stones, having more liberties, playing nearer the centre, star points and the third and fourth lines, with a penalty for the first and second lines. Early in the game it also avoids playing far away from every existing stone.
It waits about 0.6 seconds before each move. It passes only when it has no legal move left.
There is no undo, no saved games and no difficulty setting; reloading the page starts a new game.
Go — known as Baduk in Korea and Weiqi in China — is the ancient game of territory and influence. Two players place black and white stones on the intersections of a grid, competing to surround more of the board. The Board Gaming Hub build is single-player versus an AI and offers three board sizes: 9×9 for a quick game, 13×13 for a middle ground, and the full 19×19. The rules are short; the depth is famous.
Black plays first. Stones go on the intersections of the grid lines, not the squares, and once placed a stone never moves — it can only be captured. Same-color stones connected horizontally or vertically (never diagonally) form a single group that lives or dies together.
A group's liberties are the empty intersections directly adjacent to it. As long as a group has at least one liberty it stays on the board. Fill its last liberty and the whole group is captured and removed. You may not play a stone that would leave your own group with zero liberties (a suicide) — unless that same move captures an enemy group and thereby gains a liberty.
When neither player wants to add stones, they pass. Two consecutive passes end the game. The board then enters a scoring step: click any group of stones that cannot avoid capture to mark it as dead — those stones are removed and count for the surrounding player. Press Confirm / Final Score when both sides agree, or Resume Play if there is a disagreement to settle on the board.
There are two scoring traditions, and it helps to know both:
They usually give the same winner, differing by at most a point or two. This build uses area (Chinese) scoring: your score is your stones on the board plus the empty territory you enclose.
Want another two-player abstract? Chess and Othello are close cousins in the strategy shelf.