Renaissance Rules


This project is about the Western rediscovery of the complete game as played in China, Japan and Korea, including triple ko draws and (almost) unrestricted ko play.

Table of contents Table of diagrams
Double ko seki
Triple ko
Moonshine life
Sending three returning one
0-sided endgame ko
Molasses ko


AGA/NZ were the first simple and logical rules, but they also reduced the game to a less rich version by removing draw on repetition that is prevalent in Asia. Oddly enough, NZ rules at the same time reintroduced score draws with integer komi 7.

These rules avoid that reduction, with an equally simple and logical model of gameplay that handles all repetitive situations. Usable with both area and territory scoring (the latter with pass stone playout):

  • basic ko with a threefold repetition rule
    (draw/loss/win depending on stones captured in the loop)
  • minimal-superko:
    a board play must not recreate the position of the last successive two passes
  • play stops on three successive passes

In other words: two passes block later repetition of the position, three passes stop play completely.

Minimal-superko is easier to apply than normal superko since at most one position needs to be remembered, not whole history. It is also less intrusive since its effects are limited to the necessary minimum.

See also on [ext] L19.


(First draft - trivial definitions omitted, just showing the logical units and how they work together.)

1. Basic rules and trivial definitions (board, intersections, move = board play or pass, strings, liberties, capture - with [3] suicide allowable, resign, handicap)
2. Basic ko (if a single stone captures a single stone, it cannot be recaptured immediately on the next move).
3. Threefold repetition (draw/loss/win depending on stones captured in the loop). Applied for board plays only and thoughout all phases together.
4. Minimal-superko: a board play must not recreate the position of the last successive two passes.
5. Three successive passes stop the game and ends a game phase. Resumption from a stop is requestable, starting a new game phase, with intact move order, for a finite times. (First phase is "main game", later phases "dispute phases".)


A.6. A player's score is the number of intersections controlled (occupied or surrounded by his live stones), plus W komi.
A.7. In a stopped position dead strings are what their owner acknowledges, other strings alive.


B.6. A player's score is the number of intersections in his territory, plus earlier prisoners taken, plus opponent's stones in his territory ("dead stones"), plus W komi.
B.7. In a stopped position dead strings are what their owner acknowledges, other strings alive. A player's territory are the intersections that are empty or contain a dead stone of the opponent, and are surrounded by his live stones.
B.8. In dispute phases a player who passes gives a stone to the opponent as prisoner.
B.9. In dispute phases the number of moves played by both players must be equal. If necessary, the stopping passes are complemented by an obligatory extra pass of the next player.


C.6. A player's score is the number of intersections in his territory, plus earlier prisoners taken, plus opponent's stones in his territory ("dead stones"), plus W komi.
C.7. {---}

Alternative for AGA/NZ

Since AGA/NZ rules only target area scoring, they don't need three pass stops and can consider an alternative way of supporting draw on repetition. Most of their rules can remain untouched with only a slight refinement:

  • for main phase: basic ko with threefold repetition
    (draw/loss/win depending on stones captured in the loop)
  • superko only applies in dispute phases, after first resumption

Both rulesets could consider this for a future revision (at least as an option). This would make them (mostly) compatible to the Chinese game, ease the applicability problems of superko, and achieve better rulings - for negligible costs.


For rules following current Asian practice of draw on repetition, the first problem is how to differentiate between various types of cycles - most importantly triple ko and moonshine life. This is complicated further by another problem: the switch from territory scoring to pass stone playout is only safe after three passes. This creates further repetitive potential (double ko seki for example).

Three passes were proposed by various authors before (Yasunaga and others). One motivation behind them is to get rid of technical/unintended stops, where the first pass was not real, only forced by a ko ban. Three passes are also how Spight rules usually work in practice.

This is particularly important for territory scoring, to stop main play in a ko-wise complete position, before switching to pass stones. Two pass stops could allow a player to force a stop with an open ko (using excess threats), and only connect it in the pass stone phase, for one point scoring error.


1. 1-eye-flaw (dead ko)


B1 captures in the ko, forcing W2 to pass. After B3 pass, W4 would like to recapture (with or without resumption). This is a 2-pass non-perpetual repetition cycle.

Correct outcome: B is capturable with the above basic legal sequence.

RR: Neither threefold repetition nor minimal-superko intervenes here. The "repeating" position is not the one two passes occurred in. Even if B waits until two passes occur in the start position (like B1 pass, W2 pass, B3 takes ko, W4 pass, B5 pass, W6 recaptures ko) W is free to recapture because of W4/B5 passes.

2. Double ko seki

Double ko seki  

A player may try to use this position for reaching threefold repetition or preventing a stop. There is a possible 2-pass perpetual repetition cycle here: B1 flips a ko, W2 flips the other, B3 pass, W4 pass, (resumption if necessary), B5 flips a ko etc.

Correct outcome: This position is not enough for draw on repetition, and a stop is forceable.

RR: Because of B3/W4 passes, after B7 pass W8 can deviate and capture the double ko seki by flipping in it preemptively. B9 would need to restore the position to that of B3/W4 and is forbidden. This is the same behavior as normal superko without passes lifting bans. B1 was a mistake.

3. Triple ko

Triple ko  

Both players are forced to play in the cycle, to avoid getting captured. This is a no-pass perpetual repetition cycle.

Correct outcome: Draw on repetition.

Notable alternative: Although undesired in the context of these rules, blocking the cycle (forcing a player to play away) is not necessarily incorrect here either.

RR: Threefold repetition, with both players capturing the same number of stones so the result is draw. Minimal-superko can have no effect here since the position is not stable so couldn't have seen two successive passes.

4. Moonshine life

Moonshine life  

W tries to capture starting at 'a'. B resists by flipping the double ko 'b/c', then restoring 'a'. There are two possible cycles here: If W also uses the double ko there is a one-sided no-pass perpetual cycle. If W passes after the above sequence, there is a 2-pass (half)cycle.

Correct outcome: B is capturable.

RR: W waits until play stops, then starts the capture in dispute. After the above sequence, W flips the double ko himself. B cannot answer since that would recreate the initial position (which both players passed in when play stopped), so B is captured.

If B gets to play first in resumption, he can try to play elsewhere to change the board (to avoid getting captured like above). W passes in response, until B runs out of moves and passes himself. At that moment both players passed in the position, so W can start the above capture. If B tries to use the double ko instead of moves elsewhere (for infinite board-changing potential), he gets captured as seen in the double ko seki example above.

5. SendingThree-ReturningOne

Sending three returning one  

Assuming neither side wants to start the ko, B may try to use this position to reach draw on repetition or prevent a stop. There is a possible 1+1pass cycle here: B1 at 'a', W2 pass, B3 at 'b', W4 at 'c', B5 restores the start position with the marked move, W6 pass.

Correct outcome: This position is not enough for draw on repetition, and a stop is forceable.

RR: Repeating the above sequence leads to threefold repetition. But this means a loss for B since W captures two more stones with each cycle. Forcing the sequence was a mistake.

Minimal-superko has no effect here, but B could also wait for play to stop before starting repetition. This means starting from either the shown position or after 'a' - these are the two possible stable states where play could have stopped in with successive passes. In this case, if B starts from the shown position he will not be able to recapture after 'c' and will be captured. If he starts from the position after 'a', he will not be able to play more than one cycle.

6. 0-sided endgame ko

0-sided endgame ko  

(Diagram is dummy for endgame kos that neither side can fill - an actual example)

7. Molasses ko

Molasses ko  


Go rules design can be a complex topic where even the objectives are questioned sometimes. The following principles can serve as guidelines:

1. No random restrictions

The basic rules of go are undisputed. All rulesets agree on strings, capture and immediate basic ko recapture prohibition.

Moves that are legal according to these basics must not be prohibited without good reasons. Unnecessary restrictions are as bad as incorrect rulings.

2. Normal playout is king

The status and outcome of a position must depend on play - normal play with basic rules. Any differences to this must be backed with good reasons (like moonshine life).

3. Area ~= territory

The area and the territory game must stay reasonably close to each other. No significant behavior differences are tolerable, beyond minor or unavoidable things like last dame or scoring itself.


Feel free to discuss here or on [ext] L19 (more about reasons there).

Renaissance Rules last edited by jann on October 17, 2021 - 20:31
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