The next version of Many Faces of Go will include support for all 4 rule sets used in the USA (Japanese, Chinese, American, and GOE). Here's a summary of my understanding of the differences between these rules. Please help me by correcting any errors or oversights.

Thanks,
David Fotland

Japanese rules are commonly used in Japan, Korea, the USA, and Europe. The official rules are defined by the Nihon Ki-in, the Japanese professional Go association. With minor changes (most recently in 1990) they have been used in Japan for over 1200 years. [But were first published in 1949. -wjh]

Chinese rules are commonly used in China, Taiwan, Hong Kong, and Singapore. They are traditional with no single rules-making organization. They have been in use for over 2000 years.

American rules are used in American Go Association sanctioned tournaments. The official rules are defined by the American Go Association and have been in use since January 1, 1992.

GOE rules are used in tournaments sponsored by the Ing Chang-Ki Wei Ch'i Educational Foundation, and all official tournaments in Taiwan (sponsored by the R.O.C. Wei-ch'i Association. They were drafted by the ROCWA, chaired by Ing Chang-Ki, a wealthy Taiwanese industrialist. They have been in use since 1974.

All 4 rule sets define a 19x19 board, with players alternating moves and black moving first. Stones form strings that are captured when their last liberty is filled. All forbid immediate recapture of a simple ko.

Differences in the rules are:

Komi:

Japanese, Chinese, American: 5 1/2 points
GOE: 8 points (but black wins ties, so equivalent to 7 1/2)

Handicap:

Japanese, Chinese: Fixed patterns for 2 to 9 handicap stones
American: Same fixed patterns, or optionally, can be placed anywhere
GOE: Handicap plays can be made anywhere. No fixed upper limit

Repetition:

Japanese: If neither player varies from a cycle, game is played over
Chinese: If neither player varies from a cycle, game is a tie
American: Full board repetition with same player to move is forbidden
GOE: Fighting kos and disturbing kos. Play in disturbing kos not allowed. Play in fighting kos that would repeat previous position illegal. Full board repetition with same player to move illegal.

Suicide:

Japanese, Chinese, American: Illegal
GOE: Allowed if string commiting suicide has more than one stone after move that self captures.

Pass:

Japanese, Chinese, GOE: only allowed when game is over.
American: Allowed any time. Player who passes gives a prisoner to opponent.

Japanese, Chinese, GOE: 2 passes in a row.
American: 2 passes in a row with White making the last pass

Japanese: Territory minus prisoners
Chinese, GOE: Territory plus live stones
American: Either of the above.

Japanese: surrounded intersections, shared intersections are not points
Chinese, American, GOE: Shared intersections 1/2 point each, surrounded intersections are points.

Japanese: Record position. Play out local fight, with attacker to move first. If ko arises, only ko threat allowed is pass. When players agree on status, restore saved position and score it.
Chinese, American, GOE: Continue play with opponent of player who passed last moving next. When result agreed, score that position.

Japanese: Remove dead stones as prisoners. Fill prisoners into territory of same color. Rearrange territory to multiples of 5 and 10 where possible for easy counting if desired, then count surrounded points for each color.
Chinese: Remove dead stones to bowls. Count surrounded territory of one side (rearranging or adding stones from bowls if desired to make count a multiple of 10). Collect black stones into piles of 10 and count. Side counted wins if has 181 or more points. Subtract 181, double, and add 1 for winning margin.
American: Use either of the above schemes. In handicap games, if Chinese counting is used, White gets one point compensation for each handicap stone.
GOE: Remove dead stones to bowls (which held exactly 180 stones at start of game). Put 4 white stones into black territory in a square for 8 points komi. Put all stones from bowls into territory of same color. Put left over stones into territory of opposite color. Side with these left over stones loses.

Japanese, Chinese: Lose game immediately.
American: Move is taken back and replaced with a pass.
GOE: Illegal captures in ko situations are taken back without penalty. Otherwise, no penalty is specified.

Japanese, Chinese: X time per game plus Y periods of byo-yomi of Z seconds. After the X time expires, players have Z seconds to make a move. Every time they exceed Z seconds they use one of their Y byo-yomi periods. When all Y periods have expired they lose.
American: X time per game plus Y stones in Z minutes. After X time expires, players have Z minutes to play Y stones. When Y stones have been played, a new period of Z minutes with Y stones is started. If Y stones are not played in Z minutes they lose.
GOE: X time per game, with 3 overtime periods of X/6. Entering a new overtime period costs 2 points. At the end of the third period, the player loses.

Pass as ko threat:

American, Japanese, Chinese: A board play must be made before retaking a ko.
GOE: Pass is okay as a ko threat.