How to play Go
- How to play Go
- Under construction
- Game objective
- Example Counting the score
- Liberties
- Capturing
- Groups
- Suicide?
- Ko
Under construction
Yet another introduction to Go, under construction. Relevant xkcd
Game objective
- The goal is to control more area than your opponent
- Control comes from:
- Territory — Empty intersections sealed off by your stones. (Picture a flood fill: if the color can only reach your stones, the area is yours.)
- Live stones — all the intersections your stones already occupy.
Example Counting the score
Here’s an example of a finished 9x9 game.
Out of the 81 intersections:
- Black controls:
- 30 points of territory (shown with △)
- 14 stones
- 44 points total
- White controls:
- 24 points of territory (shown with ○)
- 13 stones
- 37 points total
So Black seems ahead by 7 points, but there’s another rule: to balance the game, White is given a bonus called komi. In this example, komi is 7.5 points. With komi added:
- White’s score becomes 44.5.
- Black stays at 44.
White wins by 0.5 points!
Liberties
That example was a very peaceful game: the players simply divided the board and counted the score. Most games, however, are far from peaceful — Go is war! Your opponent will try not only to invade your territory but also to capture your stones. To understand how stones are captured, we first need to learn about Liberties.
A Liberty is an empty intersection directly adjacent to a stone, either horizontally or vertically.
The White stone has 4 liberties, marked with ◻︎
Capturing
If all the liberties of a stone are occupied by the opponent’s stones, that stone is captured and removed from the board.
Capture White’s stone
When a White stone has only one liberty left, it’s said to be in atari — meaning it can be captured on the next move.
Fun fact: Nolan Bushnell named his company Atari in 1972 after this Go term!
Groups
Groups are stones of the same color that are placed horizontally or vertically adjacent to each other. Stones in a group share liberties.
White’s group has 8 liberties
If a group loses all of its liberties, the entire group is captured.
Capture White’s group
You can escape capture by extending the group and gaining additional liberties.
Save White’s stone
Suicide?
It’s illegal to place a stone where it would have no liberties — unless that move captures some opponent stones.
Capture White’s group
Playing A immediately is illegal. First you must reduce white’s liberties by playing B.
Ko
Ko is a Japanese word meaning “eternity”. Repeating the board position by capturing a single stone is illegal.
After Black plays A to reduce White’s territory, White captures at B.
It would then be illegal for Black to recapture immediately. Black must play a different move — such as reducing White’s territory. This is called a ko threat
White faces a dilemma: If White connects the ko, Black can follow up their ko threat and reduce White’s territory. So White decides to answer the ko threat.
Once the board has changed, Black can recapture the ko.
Next, White cannot immediately recapture the ko, and with no useful moves left, White passes.
Finally, Black resolves the ko fight by connecting.