Rules of Go

1. About the game of go

Go (围棋 wéiqí in Chinese, 囲碁 igo in Japanese, 바둑 baduk in Korean) is regarded as the deepest and most complex board game ever devised. Born in China more than 2,500 years ago (legend traces it back 4,000 years), it is now played by more than 40 million people worldwide, mainly in East Asia.

Go is famous for two reasons. First, despite its disarmingly simple rules, it generates boundless strategic complexity — the number of possible positions far exceeds the number of atoms in the observable universe. Second, it was the last great game to hold out against artificial intelligence: it was not until 2016 that the program AlphaGo (DeepMind) beat one of the best players in the world, Lee Sedol.

2. Equipment

A go set consists of:

• A board (goban) with a grid of 19×19 lines (361 intersections) — there are also 9×9 and 13×13 boards for learning
• 181 black stones and 180 white stones (Black has one more because Black plays first)
• Two bowls (goke) to hold the stones

Unlike backgammon, the stones are placed on the intersections (points) of the grid, not in the squares.

3. Placing stones

Here are the fundamental rules of play:

• Black plays first, then the players alternate
• On each turn, you place one stone on any empty intersection
• Stones never move once placed (unless they are captured and removed)
• You may pass your turn (say “pass”)
• The game ends when both players pass in succession

The aim is to control territory — empty intersections completely surrounded by your stones. You win if your territory, plus the prisoners you have taken, exceeds your opponent's (Japanese scoring).

4. Liberties (qi)

Every stone or group of connected stones has liberties — the empty intersections directly adjacent to it (horizontally and vertically, never diagonally).

• A stone in the middle of the board has 4 liberties
• A stone on the edge has 3 liberties
• A stone in a corner has 2 liberties

Stones of the same colour that touch each other form a group. A group shares the liberties of all its stones. If a group has no liberties left, it is captured.

5. Capture

A stone or group is captured when all its liberties are occupied by opposing stones. You then remove it from the board and keep it (as prisoners). At the end of the game, prisoners count against your opponent's score.

Suicide is forbidden

It is generally forbidden to place a stone that would immediately have no liberties (neither on its own nor as part of a group) — this is a “suicide” move. A stone that captures opposing stones is never a suicide, since it immediately regains liberties. A few rule sets (New Zealand, for example) allow the suicide of a group of several stones, but the Japanese and Chinese rules forbid it.

6. The ko rule

Ko is an anti-repetition rule. In certain situations, the two players could capture each other back and forth indefinitely — creating an endless loop.

The ko rule forbids immediately recreating a position that has just existed. If you capture a stone and create a ko, your opponent cannot immediately recapture to return to the previous position — they must first play elsewhere (a “ko threat”). If you answer that threat, your opponent may then retake the ko.

Handling kos is one of the most advanced aspects of professional go.

7. Life and death

A group is alive if your opponent cannot capture it, even with best play. The simplest way to be alive is to have two “eyes” — two separate empty intersections completely surrounded by your stones.

Why two eyes? Because your opponent cannot play in both eyes at once. Playing in just one of the two eyes would be suicide, since the stone placed would have no liberty: the group therefore always keeps at least two liberties and cannot be captured.

8. Scoring and the end of the game

The game ends by mutual agreement (two consecutive passes). The final score is worked out from:

• Territory: empty intersections surrounded exclusively by your stones
• Prisoners: opposing stones captured during the game (they count against the opponent)
• Komi: compensation given to White because Black plays first (usually 6.5 points)

The player with the most points wins. A komi of 6.5 (or 7.5, depending on the rules) means there can be no draw.

9. How to improve at go

Go has a ranking system: from beginners (30 kyu) to professionals (9 dan). Early progress is quick — you can go from beginner to 15 kyu in a few months of regular play.

• Start on a 9×9 board to get to grips with captures and territory
• Solve “tsumego” (life-and-death problems) to train your reading
• Play on OGS (Online Go Server) or the Fox Go app
• Read the “Petit traité invitant à la découverte de l'art subtil du go” (Lusson, Perec, Roubaud) or “In the Beginning” (Ishigure) for openings