Gomoku Rules: How to Play, Win & Variants
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
- This browser game offers 9×9, 13×13, and 15×15 grids of intersections; the online friend room uses 15×15
- 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.
Count the whole row: three examples
Coordinates use A–O from left to right and 1–15 from bottom to top. These are pattern fragments; other stones and turn order are omitted. In an actual game, the move that completes a legal five ends play immediately.
Under free-style rules, an overline may count as a win. Formal Renju treats Black and White differently and includes additional forbidden-move definitions. These images explain this site's house rule; use the official Renju rule text for a tournament decision.
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: The RIF rules define overlines and double-fours as forbidden, and specify how to evaluate double-threes, including exceptions. A casual shape label alone is insufficient to adjudicate a move.
- 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 move that appears to create two qualifying threes from the placed stone. Formal Renju includes rule-defined exceptions, so check whether both threes can legally become straight fours before declaring Black's move forbidden.
Double-Four
A move that creates more than one qualifying four meeting at the placed stone. The exact board and legal continuations matter; use the formal definition rather than counting nearby Black stones alone.
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 red-ringed intersection in each diagram is a candidate Black move, not a stone already played. These are isolated shape fragments to help you notice why the rule needs attention. They omit other stones and the opening procedure, so they are not complete tournament positions.
If Black plays H8, the horizontal G8–I8 and vertical H7–H9 lines each contain three Black stones. Whether both count as qualifying threes under the formal rule depends on legal extensions and the rest of the position.
Here H8 joins G8–J8 into one four and H7–H10 into another. The simple crossing makes the double-four idea visible; a formal decision still starts by identifying the exact rule set and full board.
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]
This Site's Casual Game vs Formal RIF Renju
The table below answers the questions players ask most when a casual app meets formal Renju. It compares the two rule sets directly; the section above covers free-style as a third option.
| Question | This site's casual game | Formal RIF Renju |
|---|---|---|
| Board | 9×9, 13×13, or 15×15 options | 15×15 intersections |
| Win condition | Exactly five | Five for either color; an overline also wins for White |
| Black overline | Not a win | A forbidden move if Black has not simultaneously claimed five |
| Black double-three / double-four | Allowed by this game engine | Restricted by the RIF definitions and exceptions |
| Opening | Any empty intersection | Formal tentative-player procedure using the 13 direct and 13 indirect patterns |
The RIF opening procedure: the tentative Black makes the first three moves, the tentative White chooses colors, the player now White makes the fourth move, and Black proposes two fifth moves from which White chooses. That is the published RIF procedure, not an automatic rule for every Renju event, local club, or online app. The double-three rule is also not a simple visual shortcut — the official definition includes recursive checks for whether the apparent threes can legally become straight fours, so a diagram that labels every crossing pair of threes illegal can mislead players.
A first-player-win result for unrestricted 15×15 Gomoku is useful context for why competitive rule systems address first-player advantage, but it does not automatically apply to Renju, a free-style app, another board size, or this site's exact-five rules. This site has not found a published weak or strong solution for standard Renju — a statement about the sources reviewed here, not proof that no such research can exist. See the scope note on solved games.
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. The casual vs formal Renju table above lists the exact differences.
- "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.
Can I play formal Renju on this site?
No. The built-in board is a casual exact-five game and does not validate formal Renju forbidden moves or the RIF opening procedure. It can still help with general line-reading: scanning four directions, spotting immediate wins, and checking the opponent's threats.
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?
They are names used for the same family of five-in-a-row games. The detailed rules are not always identical: check board size, whether an overline wins, and any opening restrictions before you play.
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.