Lets Talk About New Zealand Rules

I am a big fan of Chinese rules. I have heard that New Zealand rules are pretty darn close to Chinese rules. I tried looking up the actual New Zealand rules the other day, but the way they are worded, like other rulesets, is a bit hard to follow. I was hoping we could discuss how the two rulesets differ. Anyone out there that would like to rattle off some love for New Zealand :hugs:?


To those who want the quick answer, without the conversations that followed below, here is a complete list of the differences between Chinese and New Zealand rule sets:

  1. Komi: It is 7, which means that draws are possible.

  2. Suicide: Chinese doesn’t allow it. But one aspect that distinguishes New Zealand rules from several other rulesets is the lack of an additional rule that forbids suicide. In other words, you can fill the last liberty of a group of your own stones stones, resulting in self capture. This can be relevant. For example, a player can suicide two crushed stones to make a three-space, which must be responded to, because it creates an extra ko threat. For a comprehensive discussion of these differences, see Suicidal Tendencies and Positions With A Good Suicide.

  3. Game Position Repetition: Chinese uses Positional Superko, New Zealand uses Situational Superko, and Japanese doesn’t use Superko at all. To understand the difference check out: Superko, Positional Superko, Situational Superko, and the following example:

Seki Superko Analysis - CHN (PSK) vs NZ (SSK) vs Japanese (No SK).sgf (850 Bytes)

  1. Game Conclusion: Chinese games are concluded when two passes are made in a row. New Zealand games end with a verbal agreement by both players. The game is finished when both players agree that there are no more worthwhile moves. ‘Dead’ stones may then be removed from the board by mutual agreement. If they cannot agree which stones are dead they must play on. If they cannot then agree who shall move next, all stones stay on the board (are alive) and are counted.
    Note: It is believed that this can be exploited under the right circumstances. Read more about that here: Possible Exploit/Loophole in the NZ agreement phase handling. However, this potential loophole is not possible in the OGS implementation of New Zealand rules, thanks to the stone agreement phase.

  2. Handicap Games: Under Chinese rules, Black gives White compensation for handicap stones, so that the area which they occupy is not counted. Where N stones are given, N/2 is added to White’s score and N/2 is subtracted from Black’s score. Under New Zealand rules, no such compensation is given. The effect of this is that an N stone handicap is N points larger under NZ rules, than under Chinese rules. Under NZ, White passes the first N-1 moves, where N is the size of the handicap. And Komi is not to be used.
    Note: It is worth mentioning, that there is no mention of handicap in the official Chinese rules. However, this is how Handicap is most commonly implemented when utilized.


The New Zealand rules are very concise. Sensei’s Library includes the full text on its page: https://senseis.xmp.net/?NewZealandRules

I think the main differences for the NZ rules compared to the Chinese rules are that:

  1. Komi is suggested to be 7, allowing ties.
  2. Suicide is allowed.
  3. Superko rules are simplified to being just situational superko (note: in theory, the Chinese rules text also suggests superko, but it seems that in practice, tournaments using Chinese rules may judge games as annulled if certain ko cycles, such as triple ko, occur).

Another related and very concisely worded rule set is the Tromp-Taylor rules. See Sensei’s Library and here: http://tromp.github.io/go.html

EDIT: in previous version, I incorrectly said that NZ rules are PSK, while they are actually SSK.


I really like the ties and suicide changes from the Chinese rules. I’ve always found the Tromp/Taylor rules impossible to grasp. But then again I thought their claim to fame was making it easier to program Go AI, based on how they are written/worded.

One thing of note though is that NZ appears to use SSK, not PSK. At Sensei’s the New Zealand Rules / Discussion and Tromp-Taylor Rules pages both list SSK. And from the New Zealand Rules page:

A move consists of

  1. making a play so that the resulting board position does not repeat the whole board position as it was after any of that player’s previous moves or…

Compare this to the Situational Superko page:

New Zealand Rules state (reworded): It is illegal to play so that the resulting board position repeats the whole board position as it was after any of that player’s previous moves.

Definitely is SSK for NZ, which really makes me sad, because PSK is my favorite of the two. I hear SSK offers a theoretical layer of strategy, if you were to utilize SSK somehow, but it seems so rare or reserved for such Dan level genius, that it doesn’t mean much for me :smirk:.

I found this Super Ko page by Rober Jasiek that talks about the history of Super Ko. An excerpt:

  • 1975: New Zealand Go Organization: positional super ko. This was a shortened text of the Taiwanese version. Before no English text of the Japanese 1949 rules was available and an attempt of writing them down failed due to their illogic.
  • 1978: New Zealand Go Organization: situational super ko. The first version of New Zealand rules was developed.

Sorry, I was incorrect when I said that NZ rules were PSK. Thanks for clarifying.

Can I ask here what the benefit of allowing suicide is? I’ve not thought about it deeply but hopefully there is are typical examples of situations where suicide is useful. I guess some kind of under the stones tesuji life and death?


There some interesting, but uncommon, cases where the option to self-capture could be useful.


Thanks @yebellz, I’m going to summarise as: suicide is generally not useful but can sometimes provide extra ko threats or be useful in some special case capturing races. I hope that’s about right. Interesting thanks.


Then there’s the aesthetic benefit of enabling you to simplify the rules (since SSK applies to all of them, I’ll ignore it here).

Rules allowing suicide:
You can place a stone on any unoccupied intersection.

Rules prohibiting it:
You can place a stone on any unoccupied intersection

  • unless that stone removed the last remaining liberty for all stones that are member of a group by virtue of being directly connected to that intersection
    – unless that move also captures at least a single opposite-color stone.

@teapoweredrobot: For me, suicide is most exciting because you can create another KO threat out of thin air. Seems like a useful tool to me, in the ever evolving war between Sente and Gote :stuck_out_tongue_closed_eyes:

@yebellz: Oh hey, no worries. Your post inspired me to look up PSK and SSK, to learn more. While doing that I discovered those bits about NZ rules and PSK/SSK. I shared them because I thought they were interesting and I was happy to contribute. Please know there wasn’t a shred of “you were wrong yebellz, how dare you sir?!” going on there :innocent:. As always, I sincerely appreciate your time and thoughts :relieved:.


Isn’t the suicide thing derived from orders-of-operations related to each turn on a go game?

  1. Player places one of his stones on the board
  2. Player removes all stones of opposite colour that have no liberties remaining
  3. The turn ends and other player starts from 1

So with NZ rule suicide, you can place a stone to take away your last liberty, and your opponent has to play elsewhere (or pass) before taking out your captured stones. They way OGS handles it is just bit off.

I don’t think that’s how it works. In rule sets that allow it, suicides are removed before the next player moves.

Basically, the procedure is to add another step:
2a. Remove all stones of your own color that have no liberties.

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@_KoBa: What you are describing is referred to as Delayed Suicide. New Zealand rules definitely use Suicide rules (I was able to confirm this in the Suicide article on Sensei).

@everyone: I’ve finished researching the differences between New Zealand and Chinese rules. I’ve updated my first post with the total findings.


Just tested automatic komi for 9 x 9 and 13 x 13. Turns out to be 5.5. @anoek pls change it to 5.0? <3

Sadly this doesn’t seem to be a high priority. There is some discussion about it in this thread. Although if there any updates I would love to hear about them :nerd:


However, past discussion has mainly been about implementing ties as the default result of NZ games with even scores (instead of B by +0.0). My new request is to implement automatic komi as 5.0 for 9 x 9 and 13 x 13 boards (currently 5.5) to enable ranked games with integer komi for those board sizes as well (currently only possible for 19 x 19).


I thought integer komi was flat out impossible. Why is it only possible for a 19x19 board?

You tell me… it IS possible (and 7.0 is the default komi for 19 x 19 games with NZ rules), but if a moderator isn’t notified during the scoring process, an even score will result in black “winning” by 0.0 points. Ties can manually be declared by moderators in the scoring process. Ranked games with integer komi are not currently possible for 9 x 9 or 13 x 13 boards.