Renju Rules: The Complete Guide to How Renju Is Played

1. What Is Renju?

Renju (連珠 — literally "connected pearls") is the competitive, rule-governed variant of five-in-a-row that has been played in organized tournaments since 1899. It shares Gomoku's core objective — be the first to place five stones in an unbroken row — but it adds a set of forbidden move rules that apply only to Black (the first player), creating a far more balanced and strategically rich game.

While Gomoku is the casual, widely known version, Renju is the version played in national and international championships. The governing body is the Renju International Federation (RIF), founded in 1988, which organizes World Championship tournaments and maintains the official rule set. If you are interested in competitive play, Renju is the standard you will encounter.

2. Equipment and Setup

Renju uses the same equipment as Gomoku and Go:

• Board: A 15×15 grid of intersecting lines (225 intersections total). The board is always 15×15 in official Renju — the 19×19 Go board is not used.
• Stones: One set of black stones and one set of white stones. Flat, round stones (as in Go) are standard; chips or markers can be used in casual play.
• Players: Exactly two players. One plays Black, the other White.

Starting position: The board begins empty. Black always places the very first stone.

In tournament play, the choice of who plays Black and who plays White is determined by the swap2 opening protocol (described in Section 6), not by a simple coin flip. This is important because the color assignment carries strategic and fairness implications.

3. Turn Order and Stone Placement

After setup, the game proceeds as follows:

1. Black moves first, placing one black stone on any empty intersection.
2. White moves second, placing one white stone on any empty intersection.
3. Players continue alternating, one stone per turn, until the game ends.

Stones are placed on the intersections of the grid lines, not in the squares (this is the same convention as Go). Once placed, stones are never moved or captured.

Black's first move in formal tournament play must be placed on the center intersection of the board (the exact center of the 15×15 grid, at position h8 in standard Renju notation). This is a tournament rule that does not apply in casual play, but it is the standard starting point in most competitive settings.

4. Winning the Game

The win condition in Renju differs slightly between Black and White due to the forbidden move rules:

How White Wins

White wins by being the first to place five or more consecutive white stones in an unbroken horizontal, vertical, or diagonal line. Overlines (six or more in a row) still count as a win for White — there is no restriction. White also wins if Black makes a forbidden move.

How Black Wins

Black wins by placing exactly five consecutive black stones in an unbroken horizontal, vertical, or diagonal line. This is a critical distinction: six or more in a row for Black is an overline — a forbidden move — and Black loses immediately instead of winning.

5. Black's Forbidden Moves

The three forbidden move types apply only to Black. If Black places a stone that creates any of these patterns, Black loses immediately:

Double Three (三三禁手)

Black may not place a stone that simultaneously creates two or more open threes in different directions. An open three is a formation of three Black stones that can be extended in one move to an open four (four stones with both ends unblocked).

Double Four (四四禁手)

Black may not place a stone that simultaneously creates two or more fours (any four-stone formation where one more stone completes five) in different directions. Both open and closed fours count.

Overline (長連禁手)

Black may not create a line of six or more consecutive Black stones in any direction. Only exactly five wins for Black; six or more is an immediate loss.

For a complete explanation of each rule with board diagrams and examples, see our dedicated Renju Forbidden Moves guide.

6. The Swap2 Opening Protocol

The most widely used tournament opening system in Renju is Swap2. It was designed to solve the color-assignment fairness problem — since Black (first player) has a structural advantage in five-in-a-row games, neither player should be forced into a color they consider disadvantageous for the specific opening position.

Swap2 works as follows:

The swap2 protocol incentivizes the proposer to offer a balanced opening position — if the position is too favorable for Black, the opponent will simply take Black; if it is too good for White, the opponent will take White. The only way the proposer can force the opponent to choose is to offer a truly neutral position.

7. Other Tournament Opening Systems

While swap2 is the current international standard, you may encounter other opening systems in older literature or regional tournaments:

Opening System	How It Works	Used In
Swap2	3-stone offer, then choose color or extend to 5 stones	Current RIF standard, most international tournaments
Soosyrv-8	8 pre-defined 3-stone opening positions drawn randomly; players then use swap logic	Some European championships; minimizes preparation advantage
Taraguchi-10	First player places 3 stones; second player can swap or extend; if extended to 5, first player picks color from a set of 10 fifth-stone options	Hybrid system used in some Asian tournaments
Yamaguchi	First three moves are fixed (d11 pattern); White offers N fifth-stone options and Black chooses	Older system, still used in Japan

8. Draws and Time Limits

A draw occurs only if all 225 intersections are filled with no player having formed five in a row. In practice this almost never happens in Renju — the game is almost always decided before the board fills.

Tournament games are played under time controls, typically with 30–60 minutes per player, plus increment per move. Time controls vary by organization. If a player's time runs out, that player loses. Most online Renju platforms use shorter controls (5–15 minutes per player) for casual play.

9. How Renju Differs from Gomoku

If you are coming from Gomoku, here is a quick reference to the key differences:

Rule	Gomoku (Freestyle)	Renju
Board size	15×15 (sometimes 19×19)	15×15 only
Black's forbidden moves	None	Double three, double four, overline
Overline (6+ in a row)	Win for either player	Loss for Black; win for White
Opening system	None (play anywhere)	Swap2 (or Soosyrv-8, etc.) in tournaments
Game balance	Black has forced win with perfect play	Approximately balanced for both sides
Tournament body	No global governing body	Renju International Federation (RIF)

For a deeper comparison, including strategic differences and which variant suits different player types, see our Gomoku vs Renju article.

Recommended Next Reading

• Renju Forbidden Moves In Depth — Detailed explanations and board diagrams for double three, double four, and overline.
• Renju Strategy Guide — How to play Black and White effectively within Renju's rule constraints.
• Renju Openings Guide — The swap2 protocol and common opening positions explored in detail.
• Gomoku vs Renju: Key Differences — A full side-by-side comparison of the two variants.