The Game of Unlur

An introduction to this challenging board game. Invented by Jorge Gómez Arrausi, Unlur won the 2002 Unequal Forces Game Design Competition organised by the Abstract Games magazine. It is one of the games that can be played online on the Gorrion Server. Please do try it.

The game is a connection game played between two people across a hexagonal board. Both players take turns to place a piece on the board. The objective is to be the first to complete a chain of pieces that connects edges of the board. The player with the black pieces attempts to create a Y, a chain that connects three non-adjacent edges of the board while the player with the white pieces attempts to create a line, a chain that connects opposite edges of the board. Corners are common to both of the adjoining sides.

( Winning connections. )

Both players aim to create a winning connection yet the following diagrams show positions in which black cannot form a Y and in which white cannot form a line.

( Foreign connections. )

To avoid such situations, the following rule was introduced. A player will lose if he creates a connection that the other player needs to get. For black this is a connecting line and for white this is a connecting Y. So, black aims to create a Y but has to avoid forming a line, and white aims for a line and needs to avoid a Y. Corners are common to both of the adjoining sides. In the diagrams above black has lost because he has created a losing line ( left ) and white has lost because he has created a losing Y ( right ). The rule guarantees that one of the players will eventually win. The rule permits a player to make a move that simultaneously creates both a winning and a foreign connection. That player will have won.

( Winning even though the foreign connection has been created. )

White has an advantage because it takes fewer moves to create a line than to create a Y. To make the game equal Black needs a few compensation pieces. This is a feature that is unique to Unlur. The players start by playing out a short contract battle to decide the colours. They take turns to place a black piece on the board until one of the players feels that the black pieces are sufficient to counterbalance the white advantage and declares that he will play the remainder of game with the black pieces. The game then continues with the other player taking the white pieces and making the first white move. There is only one rule: a black piece cannot be placed on the edge of the board during this contract phase ( because an edge placement can be a weakness for black. )

In the following game white has just made his first move. The chances for both players are considered to be fairly equal.

( Equal chances. )

The game can be played on a range of board sizes. Size 8 ( 8 cells along each edge ) should be the minimum for a good game. Size 10 for more serious play. Size 12 if you want a deep and challenging battle.

There are three winning patterns that can occur. A winning pattern makes it impossible for one of the players to form a winning connection and a win will automatically fall into place for the other player.

The Three Edges Pattern.   The following diagram illustrates a winning pattern for black. White cannot win because he needs one of the edges that are controlled by black.

The Two Edges Pattern.   The following diagram illustrates a winning pattern for white. White controls two opposite edges and one of them is needed by black in order to create a Y. White, however, can create a winning line.

The Opposite Edges Pattern.   The following diagram illustrates another winning pattern for white. Both black and white have control of opposite edges and their chains of pieces touch. Black cannot win because he will form a losing line if he attempts to create a Y. White, however, can create a winning line.

Links.  An article about Unlur following its success in the Unequal Forces Game Design Competition used to be available at the web site of the Abstract Games Magazine at [ http://www.abstractgamesmagazine.com/unlur.html ]. An archive copy is available at [ Archive - Unlur ].

The GoRilla Game Editor.  GoRilla is an SGF reader that can be used to analyse and review games of Unlur ( and also of Go / WeiQi / Baduk, Havannah, Othello / Reversi, Hex and Kropki ). It is a compact, non-commercial program, and is available from my web page [ gorilla.html ]. I hope you will find it a useful product.

Unlur is one of the games played online on my game server, Gorrion. [ http://www.dashstofsk.net/gorrion.php ]. Please do join in the fun. I am 'dashstofsk' at the server and will welcome all challenges to a game.