Renju Rules

Renju (Japanese: 連珠) is a professional variant of the abstract strategy board game gomoku. The name "renju" means "connected pearls" in Japanese. The game is played with black and white stones on a 15×15 gridded go board.

Renju has its origins in gomoku and therefore shares most of its rules. There are two key differences between these games, however. First, renju has the rule of forbidden moves to limit Black's advantage, something gomoku does not have. Second, renju utilizes special opening rules to balance the starting positions of games.

Basic Rules

The game is played on a 15×15 grid board. Two players take turns placing stones (playing pieces) on the grid line intersections. Black moves first.

Forbidden Moves

There are certain moves that Black is not allowed to make:

• Double three – Placing a stone on an intersection which makes more than one three that meet each other in this intersection.
  • Three – A row with three stones to which one can add one more stone to attain a straight four.
  • Straight four – An unbroken row with four stones to which one can add one more stone to attain five in a row in two different ways.
• Double four – Placing a stone on an intersection which makes more than one four that meet each other in this intersection.
  • Four – A row with four stones to which one can add one more stone to attain five in a row.
• Overline – Six or more stones in an unbroken row.

If Black makes a forbidden move, then the game will be won for White. One exception is that, if Black makes a forbidden move and attains five in a row at the same time, it will still be considered a win for Black.

Pass

In the game, a player has the option to give up the right to place a stone on the board, which is referred to as passing. If both players choose to pass consecutively, the game is regarded as a draw.

Winning

Black can win the game only by placing exactly five black stones in a row (vertically, horizontally or diagonally).

White can win by either:

• Getting five (or more) white stones in a row
• Forcing Black to make a forbidden move (see above)

Opening Rules

Site uses Taraguchi-10 opening rules for gaming.

Opening rules are designed to balance the first-player advantage and ensure that both players have equal winning chances. These rules typically involve a swap procedure or stone placement restrictions during the first few moves of the game.

Taraguchi-10 Opening Rule

• The black player puts the first move in the center of the board.
• The other player may swap.
• The white player will put the 2nd move within 3x3 central square.
• The other player may swap.
• The black player will put the 3rd move within 5x5 central square.
• The other player may swap.
• The white player will put the 4th move within 7x7 central square.

The choice 1 (after the 4th move):

• The other player may swap.
• The black player will put the 5th move within 9x9 central square.
• The other player may swap.
• The white player plays the 6th move anywhere on board.

The choice 2 (after the 4th move):

• The black player puts ten 5th moves anywhere on board (symmetrical moves are not allowed).
• The white player chooses one of the offered 5th moves and plays the 6th move anywhere on board.

Terminology

• VCF (Victory by Continuous Fours) – A forced winning sequence where the attacker continuously creates threats of four, forcing the opponent to defend.
• VCT (Victory by Continuous Threats) – A forced winning sequence using various threat combinations, not limited to fours.
• Storm – A tactical position where one must find the only winning move or the only defense among many possibilities.