Renju Rules
Renju is the standardized competitive ruleset of gomoku, developed in Japan to balance Black’s first-move advantage. The only difference from free gomoku is a set of forbidden moves that apply to Black alone.
What Is Renju
- Renju keeps the same 15×15 board and the same goal — five in a row — but adds restrictions for Black so the first player cannot force a win with perfect play.
- White plays under the normal gomoku rules, so the two sides face deliberately unequal constraints.
Black’s Forbidden Moves
- Double-three (三三): Black may not create two open threes with a single stone.
- Double-four (四四): Black may not create two fours — open or straight — with a single stone.
- Overline (长连): Black may not make a line of six or more stones. Exactly five wins; six or more is a loss.
- White has no forbidden moves at all.
How Forbidden Moves Are Judged
- If Black’s stone forms a forbidden shape, Black loses immediately — unless the same stone also makes a five-in-a-row, in which case the win takes priority.
- A stone that simultaneously creates a five and a forbidden shape counts as a win, never a loss.
How White Wins
- White wins exactly like in gomoku: make an unbroken five in any direction.
- White also wins if Black commits a forbidden move, so reading Black’s threats is a core part of Renju strategy.
Renju vs Free Gomoku
- Free gomoku has no forbidden moves, and a six-in-a-row is usually counted as a win.
- Renju restricts Black and turns overlines into losses, which keeps the game fair and competitive for both sides.
Frequently Asked Questions
What is the Renju forbidden point?
A forbidden point is an intersection where Black’s stone would create a double-three, double-four, or overline. Playing there is an immediate loss for Black.
Does White have forbidden moves?
No. Only Black is restricted under Renju. White may play any legal five-in-a-row, including lines longer than five.
Why does Renju have forbidden moves?
Without them, the first player (Black) can force a win through perfect play. The restrictions remove that forced win and keep Renju balanced.