Gomoku Rules
A guide to the casual exact-five rules used by this site, plus the key differences between free-style gomoku and formal Renju.
Standard Gomoku Rules
This is the casual exact-five ruleset used by this site's browser game. Other groups and apps may use free-style or formal Renju rules, so agree on the rules before playing.
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
- This site's browser game has no passing — you place one stone on 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 this site's exact-five 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
Detailed Winning Conditions
A win is simpler to state than to spot in a real game. Here is exactly how the five-in-a-row condition is evaluated, and the edge cases that trip up beginners.
- Direction: Horizontal, vertical, and both diagonals all count. A "line" is any unbroken run of same-colored stones.
- Exactly five (this site's casual rules): You win with a run of exactly five. A run of six or more is an overline and does not win here. Formal Renju treats Black and White differently; see the RIF rules below.
- Shared end is fine: Two separate lines may meet at one stone. As long as one continuous run reaches five, you win — the other stones do not matter.
- Whoever completes five wins immediately: The game ends the moment the fifth stone is placed. It does not matter whose turn was "supposed" to come next.
- Draw: On a 15×15 board there are 225 intersections. If all are filled with no five-in-a-row, the game is a draw. In practice this is extremely rare because someone almost always breaks through first.
Equipment & Setup
Gomoku uses the same equipment as the board game Go, which is why the two are often confused at first glance.
- Board: A grid of intersections. The standard tournament size is 15×15 (225 points). Smaller 9×9 and 13×13 boards are popular for faster casual games and for teaching children.
- Stones: Typically black and white glass or plastic stones, though wooden stones are common for nicer sets. You need far fewer than a Go set because gomoku ends quickly.
- No capture: Unlike Go, stones are never captured or removed by surrounding them. Every stone stays on the board for the whole game — this is a key difference newcomers from Go must unlearn.
- First move: Black moves first by placing a single stone anywhere on the board. There is no handicap stone and no komi (compensation) in casual play.
Rule Variants
Three rule sets cover almost all gomoku you will encounter. Knowing which one you are playing changes your strategy completely.
| 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 | Official opening procedure; check the event rules | Free placement |
| Used in | Casual play | Professional tournaments | Online play |
Renju Rules (Professional)
Renju is a formal competitive ruleset related to gomoku. The word "Renju" (連珠) means "connected pearls" in Japanese. It adds restrictions on Black (the first player) and uses formal opening procedures to address first-player advantage. Tournament details should always be checked against the current RIF rules:
- 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
- Opening procedures: Formal Renju events use approved opening procedures. Consult the current event rules rather than assuming a fixed list applies to every tournament.
- 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.
The Renju International Federation (RIF) publishes the current rules used for its events. The restrictions and opening procedures are intended to make competitive play fairer than unrestricted first-player Gomoku. [Source: Renju International Federation rules]
Common Rule Misconceptions
These are the mistakes we see most often from players coming from other board games:
- "Six in a row must be an even bigger win." On this site's exact-five board it is not a win. In free-style gomoku it can be a win, and formal Renju has color-specific overline rules, so agree on the rules before playing.
- "I can pass if I have no good move." This site's browser game does not offer passing. Formal Renju rules define passing separately, so do not generalize this house rule to every tournament.
- "Stones can be moved like chess pieces." Once placed, a stone never moves. The board state only grows, never rearranges.
- "Renju and gomoku are the same game." They share the board and the goal, but Renju's forbidden moves for Black make it a different strategic game. See our Gomoku vs Renju comparison for the full breakdown.
- "Diagonals don't count." They do. A diagonal five is a perfectly valid win.
How the Rules Shape Your Strategy
The rules are not just restrictions — they define the entire strategic landscape:
- Exact-five rewards precision. On this site, six does not win, so leave an empty point for a five rather than extending into a dead six.
- No passing keeps each turn active. In this browser game, every turn must add a stone, so defence and timing matter.
- Renju has extra constraints. Black's forbidden-move rules create tactical considerations that are absent from this site's casual game. Study the official rules before treating a pattern as a forced loss.
- Agree on the balancing rules first. The first player can have an advantage in some Gomoku variants; casual groups often alternate colors or use an agreed opening rule.
For the broader history and competitive development of these rules, the Gomoku article on Wikipedia is a solid secondary reference, and the Renju International Federation publishes the official RIF rule set used in world championship play.
Common Questions About Gomoku Rules
Does a line of 6 count as a win?
On this site's exact-five board, no — a line of exactly 5 is required. In free-style gomoku, a line of 6 or more can count as a win. In formal Renju, Black overlines are forbidden while White overlines count as wins.
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.
Quick-Reference Rule Card
| Situation | Rule |
|---|---|
| Who starts? | Black. This site allows Black's first stone on any empty intersection. |
| Where do stones go? | On intersections (line crossings), not inside squares. |
| Can I move a stone? | No. Once placed, it stays for the whole game. |
| Can I pass? | Not in this site's browser game. Other rulesets may differ. |
| How do I win? | On this site: an unbroken line of exactly 5, horizontally, vertically, or diagonally. Other variants handle overlines differently. |
| What if the board fills? | Draw. Extremely rare in practice. |
House Rules for Casual Play
When you're playing with friends and not in a tournament, you don't have to follow Renju exactly. A few simple agreements keep things fair and fun:
- Swap who is Black. Because Black has an edge, alternate first player each game, or let the loser of the previous game go first next time.
- Agree on the board size. 15×15 is standard, but 13×13 or 9×9 is fine for a quick game. State it before the first stone.
- Decide on overlines. If someone makes six in a row, is that a win? In casual play many groups say yes (free-style). Just agree up front so there's no argument at the winning moment.
- Undo only in practice. Real games have no take-backs. If you're both learning, you can allow one undo per game — but say so before you start.
More Rule Questions
What happens if both players make five at once?
They can't. Players alternate, so only the player whose turn it is can complete a five. The game ends the instant the fifth stone lands.
Is there a time limit in gomoku?
Not in casual play. Tournaments use a chess-style clock with a per-move limit, but at home you can take as long as you like. Online platforms may impose a timer in ranked matches.
Can I play gomoku with pencil and paper?
Yes. Draw a grid of dots (or use our printable board) and mark moves with X and O. It's how many people first learn the game.
Is gomoku the same as five in a row?
Yes. "Gomoku" is the Japanese name and "five in a row" is the English name for the same game. Other names include Gobang, Omok (Korean), and Wuzi Qi (Chinese). The rules are identical.
What happens if I place on an occupied point?
You can't — the intersection is already taken, so the move is illegal and you must choose an empty point. In digital play the board simply rejects the tap; on a physical board, just pick another intersection.
Can children play gomoku?
Absolutely. The rules take a minute to learn and games are short, especially on a 9×9 board. It teaches pattern recognition and planning without any reading or setup. Start kids on the smaller board and let them win a few games first.
Which Rule Set Should You Use?
If you're just starting out, use this site's casual rules: exactly five wins, diagonals count, and no passing. Choose free-style only if your group wants six-in-a-row to count as a win. If you want to play formal Renju, use the current RIF rules plus the specific event regulations rather than copying a casual board's settings. Our opening patterns guide gives additional context, but it is not a tournament rulebook.