Onyx is a 2 player connection game created in 1995 by Larry Back. It deserves to be more widely known.

Players aim to form a connection linking opposite sides of the board.


Onyx starting configuration

Rules of Play

You begin with four pieces of each colour (placed as shown). Then Black and White take it in turns to place pieces on empty intersections (where allowed). A piece can be placed on the midpoint of a square only if all four corners of that square are currently unoccupied.

Capture rule

This allows a player to capture two enemy pieces in a single turn. All of the following conditions must be met:

  • the two enemy pieces occupy opposite corners of a square
  • a third corner of the square is already occupied by a piece owned by the capturing player
  • the square's midpoint is unoccupied.

The capture is executed by placing a piece on the remaining unoccupied corner of the square. If the capturing move also simultaneously completes a second square on the board where the same conditions prevail, then the move results in the capture of four enemy pieces instead of two.

A ko cycle cannot occur despite the capture rule.

The Open Variation. The game may also be played without the starting pieces.

Comprehensive Rules. For a more comprehesive set of rules please do visit the following web site:

[ext] http://www.dashstofsk.net/onyx.html

A 16x16 game in progress, standard variation

Attraction of Onyx.

So what is so good about Onyx? Well firstly the playing board is unique and used for no other game. The method of capture is also unique and the fate of a game does often rest around the ability to enforce a capture or defend against it. It adds a new element to traditional connection games in that a badly placed stone may end up being a serious liability. You need to choose your moves carefully. If you enjoy the thrust and complication of a game of Go then you will enjoy Onyx.

Online Play.

Turn based games of Onyx can be played at the dashstofsk web site, in both the standard and open variations. This site is the only place where games in the larger size ( 16x16, displayed above, or even 20x20 if you are feeling adventurous ) can be played. Please do visit.

[ext] http://www.dashstofsk.net/gorrion.php

Onyx last edited by dashstofsk on April 1, 2020 - 17:10
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