Phantom Go

    Keywords: Variant

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A snapback is captured and re-captured

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Overview

Phantom Go is a variant of Go for two players and a referee. The players only see their own stones, but they don't know where the opponent plays. The referee sees the moves of both players and takes care that they only play legal moves.

Rules

Each player has his own board, set up so that the opponent cannot see it. The referee has a board of his own on which he plays the moves of both players. He can see both player's boards.

To make a move, a player plays a stone on his own board. The referee then checks on his board whether the move is legal and informs both players about the tried move. How exactly the refereee comments on the move depends on the rule variant (see below).

As long as a player tries to play an illegal move (such as on a nonempty intersection, or suicide, or capturing back a ko), it's still his turn and he may try another move. After the player has made a legal move, the referee copies the move to his own board. Then, it's the other player's turn.

Phantom go is usually played on a 9×9 or 13×13 board.

Common Referee Rules

The referee answers each try with one of the following comments:

  • Black/White has moved, White/Black to play.
  • Black/White puts White/Black [and himself] into atari.
    Only if the stones were not in atari before the move.
  • Black/White has captured the following stones.
    After which he points out exactly which stones were captured to both players.
    If a move both captures and puts some stones into atari, the referee says both.
  • Illegal move.
  • Black/White passes.

The referee does NOT say:

  • Which stones have been put into atari.
  • Which stones are still in atari.
  • Which stones are no longer in atari.
  • For what reason the move was illegal (such as a stone already being present, or suicide, or ko).

Example

[Diagram]

A snapback is captured and re-captured


A snapback sounds like this:

B1: Black puts a white group into atari.
W2: White has played, Black to play.
B3: Black captures the stone at a and puts White and himself into atari.
W4: White captures the 3 stones at b, c and d.

Hamburg Referee Rules

The referee answers each try with one of the following comments:

  • Black/White has moved, White/Black to move.
  • Black/White [captures n stones and] puts White/Black [and himself] into atari.
  • There is already an opponent’s stone.
  • There is already an own stone.
  • Suicide.
  • The ko cannot be captured back immediately.
  • Black/White passes.

The referee does NOT say:

  • Which of the stones have been put into atari.
  • How many stones have been put into atari.
  • Which stones are no longer in atari.
  • Which of the stones have been captured.

Miscellaneous

Phantom Go needs a lot of physical space since the players sit back-to-back and the referee stands between them. Each of the three needs a table with a board, stones and bowls.

There is an Android app called [ext] Phantom Go that allows two players to play Phantom Go using a single phone or tablet. The app takes the role of the referee.

Discussion

Bill: I have played a form of this game, which we called Kriegspiel Go, after the similar chess variant. The referee only informed the players when it was their turn, prevented illegal moves (the opponent could hear him do that), and removed captured stones. A 9x9 board was large enough. ;-)


Jan: I've also played it that way, but the information about ataris tends to speed up the game and provides some extra confusion... I'm the second best Phantom Go player in Utrecht, by the way :-)


axd: subvariant moved to new FogOfWar.

To be merged

Phantom Go was played in New Zealand from about the late 1970s but I don't know if we invented it or not.

axd: See also an [ext] article at New Scientist. It refers to Rengo Kriegspiel as a way to defeat computers.

Phelan: I had read the article before, and it seems to disregard the fact that the computer player would be much better at keeping the board in memory. It just needs to record the result of its moves to get a picture of the board. A human would have to deal with faulty memory. It would at least require much more memorization skills than usually, probably comparable to the efforts of blind go players.

If i understand correct, then the point is to find a position where either enemy stone is present, or if it's not, it's good place to play. Thus it might be good to try and check as many positions in a move as possible. Unless a failure durng piece placement means you pass a turn. This already, in an elegant way, introduces a common factor of "fog of war" games - deception. I can place my pieces in a way that would be most foolish in ordinary Go, but it will trick my oponnent into expecting one of several other formations. He should be then tricked into placing a stone in position favorable for me. -- e7th04sh

See also


Phantom Go last edited by RolandIllig on September 16, 2018 - 11:01
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