KGS Supported Rule Sets

KGS (formerly known as the Kiseido Go Server) supports several different rule sets, named after either the organization that uses them or the country where they are common. In some cases the rule sets implemented are not quite the official rules for the organization that they are named after; for example, several different rule sets are allowed in an AGA tournament. The following rule sets are used on KGS:

Image of ruleset selection menu

Japanese: In a Japanese game, the score is the sum of captures and territory. Seki does not count as territory. If the board enters a long repeating cycle that neither player wants to break, the game is scored as no-result. Note: The Japanese system of solving disputes that happen at the end of the game is not available. If players cannot agree whether a group is alive or dead, they must accept the judgement of a third neutral player.
Chinese: In a Chinese game, the score is the sum of territory and stones on the board. A superko rule is used to prevent long repeating cycles. If players disagree about the life and death of stones after the game ends, they simply undo and play out the situation. The white player is given one point extra komi for every handicap stone that Black gets at the start of the game. Note: There is some ambiguity in the official Chinese rules regarding ko and ending the game. The rules used on KGS are believed to be the most accurate interpretation possible.
AGA: AGA (American Go Association) rules on KGS use the "area counting" option. That is, they are played the same as Chinese rules, except that the white player is given one point of extra komi for all but the first handicap stone that Black gets at the start of the game. The AGA also lets players count the score by territory, as in Japanese scoring, but the AGA rules are set up so that the two scoring systems always give exactly the same final result for the game. Since KGS always does the counting for the players, which system is actually used doesn't matter.
New Zealand: New Zealand rules are like Chinese rules except that playing a multi-stone suicide move is allowed. This is the only rule set that permits this kind of suicide.

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