• Players alternate placing one stone per turn on any empty intersection of the 15×15 board.
• Get 5 of your own stones in a row — horizontal, vertical, or diagonal — to win. No captures, no removing pieces.
• In Freestyle, any 5-or-more in a row wins. In Standard (Renju), the first player is barred from certain "forbidden points" (double-three, double-four, six-or-more in a row) — marked with an × on the board; the second player has no such restriction.
• If all 225 points fill up with no winner, the game is a draw.

Gomoku (五目, "five points") is its own classic board game, not part of the Gonu family — added here alongside PlayGonu's Korean Gonu variants since it shares the same simple pencil-and-paper spirit.