Onyx

Opening Position

No. of Players

Two

Equipment

An Onyx board and (theoretically) 102 each of black and white counters are required for play. Realistically, however, probably far less counters will be used before one player wins the game.

History

Onyx was invented by Larry Back in 1995. Onyx was featured in several issues of Abstract Games magazine edited by Kerry Handscomb.

Objective

The objective is to be the first player to build an unbroken line of counters of one’s own color connecting the two opposite sides of the board assigned to that same color. The player with black attempts to make a vertical connection, while white aims for a horizontal connection. The nodes in the corners of the board are common to both players.

Play

The board is setup with the initial position shown above. Similar to most connection games, alternate turns entail the placing a of a single friendly counter at a vacant node on the board with black placing first and utilizing the pie rule. Onyx, however, has a few additional rules adding a little more depth to the play. The midpoint rule says that a player may place a counter at the midpoint of a square (darker regions) only if none of the four corners of the square are occupied. Unique among connection games, Onyx allows for capture of opposing counters during the course of a game. If the midpoint node of a 'square' is unoccupied a player can capture by completing a configuration in which all four corners of the square are occupied with both players occupying opposite corners of the square. The other player's pieces are then removed from the square. To clarify: to capture two enemy counters in a single turn all of the following conditions must be met:

the two opposing counters occupy opposite corners of a square
a third corner of the square is occupied by a counter belonging to the capturing player
the square's midpoint is unoccupied

If all of the conditions are met, the capture is executed by placing a friendly counter on the remaining unoccupied corner of the square. A double capture is also allowed: 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 counters instead of two.

Variations

The game may also commence with the board vacant of counters. A larger board can be used.

Sources