What is Renju?

Renju (連珠) is the official competitive variant of Gomoku, played on a 15×15 board with the same goal: get exactly five stones in a row horizontally, vertically, or diagonally. The key difference is that Black (the first player) is subject to forbidden moves that the computer doesn't enforce on this platform — you apply them yourself, which is exactly how the game is taught to new competitive players.

Renju has its own international governing body (the Renju International Federation, RIF) and hosts a World Renju Championship. It is the most strategically serious form of five-in-a-row played competitively.

Black's Forbidden Moves — Quick Reference

These three move types are illegal for Black in standard Renju. White has no restrictions.

Forbidden Move	Definition	Consequence
❌ Double-Three (33)	A single move that simultaneously creates two "open three" sequences — three in a row with both ends unblocked	Illegal — Black must choose a different cell
❌ Double-Four (44)	A single move that simultaneously creates two four-in-a-row sequences (open or semi-open)	Illegal — Black must choose a different cell
❌ Overline (6+)	Six or more consecutive Black stones in a row — does not count as a win for Black	Not a win; Black must reach exactly five

White can freely create double-threes, double-fours, and overlines. White also wins with an overline (six in a row).

How to Play Renju on This Platform

Our game engine uses the standard Gomoku ruleset. When playing Renju:

1. Both players agree to Renju rules before starting the game.
2. Black self-enforces forbidden moves — before each move, quickly check whether your stone would create a 33, 44, or overline. If it would, choose a different cell.
3. The forbidden moves reference card is displayed at the top of the play page for easy reference during the game.
4. If a disputed position arises, refer to the full Renju rules article for clarification.

Renju vs Gomoku: Which Should You Play?

If you're new to five-in-a-row, start with standard Gomoku online — no restrictions, pure strategy. Once you're comfortable with tactics like open fours, forks, and VCF sequences, Renju adds another layer of depth by forcing you to find legal winning paths that don't trip the forbidden move rules.

Experienced players often find Renju more satisfying because it's genuinely balanced — Black can't just bulldoze with the most powerful double-threat, requiring more creative and nuanced play.

For a complete comparison, see our Gomoku vs Renju guide.

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Learn Renju — In-Depth Guides

New to Renju or want to sharpen your game? These articles cover everything from the basic rules to advanced strategy and the history behind the game.