This is a summary of the AGA rules of play as interpreted by the BGA and is intended to highlight the main differences from previous rules used.
Wheneveryou pass you must hand a 'pass stone' to your opponent as a prisoner.
You must not play so as to re-create a previous board position that you created on a previous play.
A move which violates the rules of ko, superko, self-capture, or alternation is an illegal move. Any other violation of the rules is an irregularity. It is assumed that any violation is made inadvertently. Please see the section Illegal and Irregular Moves for details.
Play pauses when both players pass in succession. You then attempt to reach agreement on all the stones that should be removed without further play.
If such agreement cannot be reached, then play resumes with the opponent of the last person to pass moving first. If the first two moves of a resumption are pass, then the game ends with all stones remaining on the board.
Once agreement is reached, or the game ended on a total of 4 consecutive passes, White must make an additional pass if Black was the last to pass.
At the start of the game you can agree to use Territory counting or Area counting, and if you cannot agree, then Territory counting is used. Territory is defined as empty intersections surrounded by stones of the same colour. So eye points in seki count towards territory.
The clock must be stopped while players attempt to resolve any issue surrounding rule violation. If there is any doubt or dispute as to how to proceed, please call the referee.
In the case of a failure of alternation, the phrase "illegal move" in this section refers to the whole sequence of two or more moves played consecutively by the offending player.
If you inadvertently make an illegal move and if the error is noticed immediately, unwind to the position before the illegal move and pass, handing a pass stone to your opponent.
If the illegal move is noticed after one or more intervening moves then, by mutual agreement, the players may rewind to the position before the illegal move. The offender then plays a legal move without handing over a pass stone.
If the players do not agree to unwind, then play continues as is, except that, in the case of self-capture, the relevant stones should be removed from the board and handed to the opponent as prisoners.
If you inadvertently make an irregular move then as soon as the error is noticed, fix the position as best you can to the satisfaction of you and your opponent. Here are examples of irregular moves with the commonly accepted fixes: