# Connect 6

Keywords: Opening

Connect6 was introduced by Professor I-Chen Wu at Department of Computer Science and Information Engineering, National Chiao Tung University, is a two-player game similar to Gomoku.

Connect6 was designed as complex and hard to brute-force by computers. It have tree complexity of ≈10^172 (GO at 19x19 board have in comparsion tree complexity of ≈10^171.

Two players, Black and White, alternately place two stones of their own colour, Black and White respectively, on empty intersections of a Go-like board, except that Black (the first player) places one stone only for the first move. The one who gets six or more stones in a row (horizontally, vertically or diagonally) first wins the game.

The handicap of black's only being able to play one stone on the first turn means that the game is comparatively fair; unlike similar games such as Gomoku has been proven to give the first player a large advantage, possibly no additional compensation is necessary to make the game fair.

### Game Rules

The rules of Connect6 are very simple and similar to the traditional game of Gomoku:

• Players and stones: There are two players. Black plays first, and White second. Each player plays with an appropriate color of stones, as in Go and Gomoku.
• Game board: Connect6 is played on a square board made up of orthogonal lines, with each intersection capable of holding one stone. In theory, the game board can be any finite size from 1×1 up (integers only), or it could be of infinite size. However, boards that are too small may lack strategy (boards smaller than 6×6 are automatic draws), and extremely large or infinite boards are of little practical use. 19×19 Go boards might be the most convenient for beginners.

Professional games are played on 59x59 boards 9 gobans tiled in a square.

• Game moves: Black plays first, putting one black stone on one intersection. Subsequently, White and Black take turns, placing two stones on two different unoccupied spaces each turn.
• Winner: The player who is the first to get six or more stones in a row (horizontally, vertically, or diagonally) wins. (This is a departure from Gomoku, where it must be exactly five in a row.)

There is an proposal to make connect6 one of the games for played at the computer olympiad see http://www.cs.unimaas.nl/olympiad2006/connect6.pdf