It was played with black and white stones on a Go board (19×19 grid).
In China it was called Wu Zi Qi (五子棋), meaning five stones.
Japan
The game spread to Japan around the Heian period (794–1185 CE).
It became known as Gomoku Narabe (五目並べ), which means five pieces in a row.
Usually played on a 15×15 grid there, rather than the full Go board.
Korea
The game was adopted under the name Omok (오목).
Europe & the West
In the 19th century, it arrived in Europe (especially the UK), where it was called Gobang.
A simpler variant, tic-tac-toe (3 in a row on 3×3), also spread in the West as a paper game.
Modern Era
In the late 19th century, Japan developed Renju, a professional rule set with restrictions on the first player (since otherwise the starting player always has a winning strategy).
Today, Gomoku and Renju are played worldwide, both as casual pencil-and-paper games and in official tournaments.
There are international federations, and World Championships have been held since 1989.
Rules of the Game
Classic Gomoku
Board: Usually a 15×15 grid (sometimes 19×19).
Players: One uses X (or black stones), the other O (or white stones).
Turns: Players alternate placing their mark on an empty cell.
Objective: First player to align exactly 5 in a row (horizontally, vertically, or diagonally) wins.
Longer lines (6 or more) still count as a win in casual Gomoku.
No moves can be undone once placed.
Renju (Tournament Rules)
Designed to balance play, because the first player has a strong advantage.
Restrictions on the first player (Black):
Cannot win with more than 5 in a row (overline).
Forbidden to create two “open threes” or two “open fours” in one move (double-three or double-four rules).
Opening rules: often use a swap rule, where after the first few moves the second player can choose sides, making the start fairer.