Copyright (c) 2004 Fred Horn

This game is played on a 19x19 Go board:


Definition of Bisector: the orthogonal line intersecting the midpoint of the line segment defined by two stones.

  • TURN - On his turn, each player drops two friendly stones on empty cells provided that:
    • both stones occupy the same line with an odd number >= 3 of empty cells between them (ie, the midpoint corresponds to an intersection),
    • the line must be the bisector of the previous move (this restriction does not apply, of course, in the first move of the game),
    • the previous midpoint and the closest stone must have one or more empty cells between them
    • it is illegal to place a stone between already played two stones of a used line
    • the new bisector must not have be played before (ie, there's a maximum of 19 moves/player on a 19x19 Go board).
  • GOAL - A player without a legal move loses the game.
An example

The left diagram show the beginning of a sample match. The green dots represent the respective midpoints.

Notice that now, the Second player for his next move, cannot place a stone at the red dots (there must always by a line of empty cells between the new stones and the previous midpoint.

Also, all intersections between each pair of stones cannot be used in the following moves.

Fred Horn, in the original rules, states White as the first player.