Copyright (c) 1992 Mark Steere

Quadrature is a two player strategy game played on a 11x11 square board. This is the initial configuration. Each player has a set of 16 stones. Players start with 9 stones on the board with 7 held in reserve. Players also have "markers" explained later.

MOVE - Players take turns making basic moves. A basic move is to move a stone *one space* forward, diagonally forward, or sideways. Players cannot move backwards or diagonally backwards.
SQUARING - an aggressive maneuver in Quadrature. To "square" an enemy stone, you move to form a rectangle on the board with three of your stones and one enemy stone. So you have three "squaring" stones and one "squared" stone. The enemy "squared" stone is then removed from the board and replaced with one of your own reserve stones. Removed stones are returned to their original owners. Players do not take ownership of each others stones.
CHAIN REACTION - it can happen in Quadrature. When you replace an enemy stone with one of your own reserve stones, your newly added stone can square additional enemy stones.
GOAL - There are two ways to win in Quadrature. If you kill enough enemy stones to leave your opponent with two or less stones on the board, you win. Also, if you can get three of your stones onto the enemy "home plate", you win. A player's home plate consists of the three points in the middle of his side of the board.
MARKER - Each player has a marker which is a flat square chip. Each player's marker is the same color as his stones. The marker has a single dot on one face and two dots on the opposite face.
If you make a non-aggressive, sideways move, you must place your marker on the board with the single dot face up. You can put it anywhere on the board. The location doesn't matter; it's just showing that you made one non-aggressive sideways move. If your marker is already on the board with the single dot face up, and you make a non-aggressive sideways move, you must flip your marker over so that the two-dot face is showing. This shows that you have made two consecutive, non-aggressive sideways moves. A non-aggressive sideways move is a sideways move which does not kill any enemy stones.
If your marker is on the board with the two-dot face showing, you are not allowed to make a non-aggressive sideways move. You must make a forward, diagonally forward, or aggressive sideways move. An aggressive sideways move kills enemy stones. Once you have made a forward, diagonally forward, or aggressive sideways move, you must remove your marker from the board. It doesn't matter if it is showing a single dot or two dots; a forward move always clears your marker from the board.
There is no limit to the total number of non-aggressive sideways moves you can make. You just can't make more than two non-aggressive sideways moves consecutively.
This rule was instated because players have a tendency to approach each other and then stall the game by making an endless series of non-aggressive sideways moves. The marker forces players to engage each other in combat, no matter how reluctant they may be.
SUICIDE - You must not move an on-board stone to any point that completes an enemy square. Suicide moves are not allowed, no matter what.

An example

If Black moves to [1], he will square the white stone to his left, and produce a chain reaction that will square the other white stone. White will loose, since it will have just two stones. The home plates are represented in the example by the red points.

The game can be played at Rognlie´s PbeM server.