Gomoku, also called go-moku (Japanese for "five points") is a tic-tac-toe-like game in which two players alternately place pieces, with each player using pieces
of a fixed color, in an attempt to place five (or more) pieces in a row (horizontally,
vertically, or diagonally). The game is traditionally played on a go
board of size 
,
although 
and 
boards are also common. By convention, play opens with
black.
In standard gomoku, rows of exactly five piece are required for a win, so if a row longer than five pieces (called an overline) is created, it does not count as a win. In free-style gomoku, overlines also count as wins.
On a 
board, black can always win
with optimal play in either the standard or free-style variants (Allis 1994).
