Gomoku Rules
Complete guide to the rules of gomoku (five in a row). Covers the standard rules used in casual play as well as the Renju and free-style variants played in tournaments.
Standard Gomoku Rules
These are the most commonly played rules, used in casual games worldwide.
1. Board Setup
- The game is played on a 15×15 grid of intersections (same board as Go)
- One player uses black stones, the other uses white stones
- Black always goes first
2. Gameplay
- Players take turns placing one stone per turn on any empty intersection
- Stones are placed on the intersections (where grid lines cross), not inside the squares
- Once placed, a stone cannot be moved or removed
- There is no passing — you must place a stone each turn
3. Winning
- The first player to form an unbroken line of exactly 5 stones wins
- The line can be horizontal, vertical, or diagonal
- In standard rules, a line of 6 or more stones does NOT count as a win (overline rule)
- If the board fills up without either player making five in a row, the game is a draw
Rule Variants
| Rule | Standard | Renju | Free-Style |
|---|---|---|---|
| Overline (6+) | Not a win | Forbidden for Black | Counts as win |
| Black restrictions | None | Double-three, double-four, overline forbidden | None |
| Opening rules | Free placement | Designated openings (26 patterns) | Free placement |
| Used in | Casual play | Professional tournaments | Online play |
Renju Rules (Professional)
Renju is the professional variant of gomoku, developed in Japan in the early 20th century. The word "Renju" (連珠) means "connected pearls" in Japanese. It adds restrictions on Black (the first player) to compensate for Black's proven first-move advantage:
- Forbidden moves for Black: Double-three (creating two open threes simultaneously), double-four (creating two fours simultaneously), and overline (six or more in a row)
- White has no restrictions — White can form overlines, double-threes, and double-fours freely
- 26 designated openings: The first three moves must follow one of 26 approved patterns (see opening patterns)
- If Black makes a forbidden move, Black loses
Renju Forbidden Moves Explained
The forbidden move rule is the heart of Renju. Here's what each restriction means:
Double-Three
A single move that simultaneously creates two open threes (lines of 3 with both ends open). This is forbidden because it creates an unstoppable threat — blocking one open three leaves the other to become an open four.
Double-Four
A single move that simultaneously creates two lines of four. Since each four only needs one more stone to become five, blocking one four leaves the other to win. This is forbidden for the same reason as double-three.
Overline
A line of six or more stones in a row. In Renju, only exactly five counts as a win for Black. An overline is not a win — it's explicitly forbidden. White can still win with an overline.
According to the Renju International Federation (RIF), these restrictions were introduced to create a balanced and skill-based game. Without them, Black's first-move advantage would make competitive play uninteresting. The RIF was founded in 1988 and organizes the Renju World Championship. [Source: Renju International Federation, renju.net]
Common Questions About Gomoku Rules
Does a line of 6 count as a win?
In standard rules, no — a line of exactly 5 is required. In free-style gomoku, a line of 6 or more does count as a win. In Renju, overlines are forbidden for Black.
Can I play on a smaller board?
Yes! 9×9 and 13×13 boards are common for casual and beginner play. See all board sizes →
Why does Black go first?
Tradition from Go, which uses the same equipment. In gomoku, going first is a significant advantage — this is why Renju adds restrictions on Black.