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X-0 Rules

X-0 is a Gomoku variant with fouls (forbidden moves) for Black. Played on a 15×15 board.

Objective

Be the first to build exactly five stones of your color in a row — horizontally, vertically, or diagonally.

Basic Rules

• Black (X) always moves first.
• Players take turns placing one stone on an intersection.
• The first to form exactly 5 stones in a row wins.

Fouls (Forbidden Moves) for Black

To compensate for the first-move advantage, Black has restrictions. White has no fouls.

• 3×3 Foul (Double Three): Black may not place a stone that simultaneously creates two open threes. An open three is three stones in a row that can be extended to five from both ends.
• 4×4 Foul (Double Four): Black may not place a stone that simultaneously creates two fours.
• Overline Foul: Black may not create a row of 6 or more stones. Only exactly 5 counts.

The only legal fork for Black: 4×3 (one four + one open three).

White (O)

White has no fouls. White can win with 3×3 forks, 4×4 forks, or overlines (6+). White also wins if Black accidentally makes a forbidden move.

Draw

If the board is completely filled and no player has built 5 in a row — the game is a draw.

Gomoku Rules (Swap2)

Gomoku is the classic version without fouls. All rows of exactly 5 stones win, regardless of color.

Swap2 Opening

Swap2 is the standard tournament opening in Gomoku, designed to eliminate the first-move advantage. It consists of two phases.

Phase 1: Placement (Placer)

The first player (Placer) places 3 stones anywhere on the board:

• 2 black stones (X)
• 1 white stone (O)

Phase 2: Choice (Chooser)

The second player (Chooser) picks one of three options:

• Play Black: takes X, opponent gets O. Black makes the next move.
• Play White: keeps O, opponent gets X. Black makes the next move.
• Add 2 stones: Chooser places 1 more black + 1 more white (5 total on board), then Placer chooses the color.

After the Opening

Standard Gomoku rules apply: 5 stones in a row = win. No fouls. Rows of 6+ stones do not count as a win.

Why It Works

Swap2 motivates the Placer to create a maximally balanced position: if the initial placement favors Black — Chooser takes Black. If it favors White — Chooser stays White. If perfectly balanced — add 2 more stones and return the choice.

Renju Rules (Taraguchi-10)

Renju is the professional version with fouls for Black and the complex Taraguchi-10 opening (5 phases).

Renju Fouls

Same as X-0, Black is forbidden: 3×3, 4×4, overline (6+). White plays without restrictions.

Taraguchi-10 Opening (5 Phases)

Phase 1 — First Move (Black)

Black places the first stone exactly in the center (7,7). The opponent may swap colors.

Phase 2 — Second Move (White)

White places the second stone within the 3×3 square around the center. The opponent may swap colors.

Phase 3 — Third Move (Black)

Black places the third stone within the 5×5 square around the center. This creates one of 26 canonical openings. The opponent may swap colors.

Phase 4 — Fourth Move (White)

White places the fourth stone within the 7×7 square around the center.

Phase 5 — Fifth Move (Black)

Black has two options:

• Choice 1 (Normal): Black places one 5th stone within the 9×9 square. Opponent may swap colors. White makes the 6th move.
• Choice 2 (Taraguchi-10): Black waives all swap rights and places 10 candidate 5th moves (no symmetrical duplicates). White chooses one and removes the other 9. White then makes the 6th move.

How It's Implemented on X-0

The Taraguchi-10 opening is implemented with visual guidance at each step:

• The system highlights valid zones for each move (3×3, 5×5, 7×7, 9×9).
• The Swap button lets you switch colors during phases 1-4 and Choice 1 of phase 5.
• In phase 5 Choice 2 (Taraguchi-10), an interface appears for placing 10 candidate moves.
• White sees all 10 candidates and selects one by clicking.