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Gomoku

15×15 · Renju rules · Black restrictions · Black moves first

Rules and strategy

Black to move

Black wins with exactly five; White with five or more.

Moves: 0
Saved on this device

Standard · 30s/move

Black

You

Running

This move00:30

White

Computer

Waiting

Next move00:30
Black · Time left for this move00:30

Arrow keys to move · Enter or Space to play

Last move (square)

Gomoku rules and strategy

New here? Start with the essentials. Otherwise jump to a diagram or strategy.

Start with these rules

  1. Alternate on empty intersections

    Black starts on a 15×15 board. Put stones where the lines cross, not inside the squares.

  2. Exactly five for Black; five or more for White

    Connect consecutive stones horizontally, vertically or diagonally. Placed stones do not move.

  3. Check Black’s forbidden moves

    Double-threes, double-fours and overlines are forbidden. Compare the diagrams below.

Back to the board

See it on the board

A gap can be the winning point

Black at A joins the separated stones into exactly five. Check gaps between stones as well as the ends.

Before the moveA
Before the move
After the moveA
After the move

A marks the stone placed in this diagram. An enlarged part of the full board.

Forbidden moves for Black

Forbidden diagrams imagine a black stone at A. The playable game rejects that move.

First, recognize an open three

These three stones can become an unbroken four with two open winning ends through a legal next move. Counting any three stones is not enough.

An open threeA
An open three
An open four on the next moveA
An open four on the next move

Adding one stone beside the open three makes a four that can become five at either end.

Small blue rings mark possible next connections.

Forbidden for Black

Double-three · two open threes at once

Black at A creates one horizontal and one vertical open three. Each can legally grow into an open four, so this is a forbidden double-three.

Black at A creates one horizontal and one vertical open three. Each can legally grow into an open four, so this is a forbidden double-three.A

Forbidden for Black

Double-four · two fours at once

Black at A creates a horizontal four and a vertical four. Each can become five on the next move, making this a forbidden double-four.

Black at A creates a horizontal four and a vertical four. Each can become five on the next move, making this a forbidden double-four.A

Forbidden for Black

Overline · six or more in a row

Filling A joins six consecutive black stones. This is forbidden for Black; the same pattern made with white stones wins.

Filling A joins six consecutive black stones. This is forbidden for Black; the same pattern made with white stones wins.A

Legal for Black

One open four is not a double-four

This single four has two winning ends, but it is still one four. Two winning points do not mean two different fours.

This single four has two winning ends, but it is still one four. Two winning points do not mean two different fours.A

Legal for Black

A blocked three is different

White blocks the horizontal line from becoming an open four. Only the vertical three is open, so this example is not a double-three.

White blocks the horizontal line from becoming an open four. Only the vertical three is open, so this example is not a double-three.A

Only Black has these restrictions. On this site, completing exactly five on the same move takes priority as a win.

Three strategies to learn first

  1. Look for your own winning move first

    First check whether a legal move can complete your winning line immediately.

    First check whether a legal move can complete your winning line immediately.A
    Read the details

    Read the open ends, not just the stone count

    Four connected stones with both ends blocked by an opponent or the edge cannot immediately become five. Four with one open end is an urgent threat: a stone on that end can complete the line.

    Four with both ends open leaves another winning end if one is blocked. But if the opponent can complete five first, the game ends before your attack. Check immediate threats even when your own shape looks strong.

    Practice: the gap in the middle can win

    Imagine your stones as stone, stone, gap, stone, stone along a line. Filling the middle joins five consecutive stones. Looking only at the outer ends can miss this winning gap.

    Filling the gap between three of your stones and two more creates six. White wins with this shape, but Black cannot play it because it is an overline. Check the color and legality when defending against the same pattern.

  2. Stop the opponent’s next win

    Black already blocks one end of White’s four. Playing at A stops the immediate win along this line.

    Black already blocks one end of White’s four. Playing at A stops the immediate win along this line.A
    Read the details

    A short checklist for your next move

    Begin by noticing what can win or lose on the very next turn. Focus on connections near existing stones rather than treating every empty point equally.

    • Can a legal move make exactly five for Black, or five or more for White?
    • If not, where could the opponent win next? Are there several independent winning points?
    • With urgent threats handled, can you extend your line and limit theirs?
    • What is the opponent’s strongest reply?

  3. Read different directions together

    A creates a horizontal four and a vertical open three. This four-three is legal for Black, but other positions still need checks for forbidden moves and faster opposing wins.

    A creates a horizontal four and a vertical open three. This four-three is legal for Black, but other positions still need checks for forbidden moves and faster opposing wins.A
    Read the details

    Look at two directions together

    Extending only one line makes your plan easier to block. Look for moves that improve both a horizontal and a diagonal connection. Identify the specific winning points created in each direction.

    Two promising shapes do not guarantee victory. An opponent may block both with one stone, an edge may close a line, or the opponent may have a faster win. The center offers more directions, but does not itself guarantee a win.

More questions

Full rules and starting your first game

Gomoku rules: this board uses Renju restrictions

Black starts, and the players alternate placing one stone on an empty intersection of a 15×15 board. Black wins with exactly five consecutive stones horizontally, vertically or diagonally; White wins with five or more. Stones are not moved or captured.

Black may not make a double-three, double-four or an overline of six or more. White has no such restrictions. A move that also completes exactly five for Black is treated as a win first. Forbidden clicks are rejected with an explanation, rather than losing the game immediately. A full board without a winner is a draw. Black automatically passes if no legal move remains.

Starting your first game

Choose the computer for solo practice or two players on one device. Random matching and friend invites are separate online modes available when the service is configured. Check the current color before placing a stone.

  • Black starts and has forbidden moves. There is no tournament opening or swap procedure: begin on any legal empty intersection.
  • Before building your own line, check whether your opponent can win on the next move.
  • After each move, inspect the horizontal, vertical and diagonal lines it changes. Try a different choice on the next board.
How are difficult forbidden moves judged?

FAQ: what counts as a forbidden move?

Only Black is restricted from double-threes, double-fours and overlines. One open four counts as one four even with two winning ends; two different fours in the same direction can still be a double-four. An open three must extend legally to an unbroken open four. A shape blocked by White or the edge, or one requiring a forbidden extension, is not counted as an open three.

Diagonals count as winning lines. A gap or opposing stone breaks a consecutive line; you cannot skip over it. Mixing black and white stones does not make a winning five.

Computer, two players and reviewing a game

FAQ: computer or two players?

Against the computer, it plays on its own turn after you. It is a practice opponent and is not guaranteed to choose the best move in every position. In local two-player mode, both people place their own stones in turn.

When reviewing a loss, look before the final move: when did the opponent first get a winning point? Compare another choice to see whether one move could have stopped it.

Clocks and move sounds

Clocks and move sounds

Play without a per-move or total time limit. There is no loss on time. Choose a fresh time limit per move, a total budget for each player, or both. Total time runs only on your own turn. With both limits, the first to expire loses the game; unused move time is not added or carried over. The computer follows the same limits while calculating.

Presets: Blitz · 15s/move / Standard · 30s/move / Long · 60s/move. These are casual settings for this site, not universal tournament time rules. The clock starts with a new game and is not reset by leaving the tab or refreshing. Undo restores the clock balances from before that move. Enter your total time separately from the per-move presets. 10 or 10:00 means 10 minutes; 5:30 means 5 minutes 30 seconds. Combined mode uses the same custom total.

Gomoku uses a short, clear stone-contact sound. Toggle it with the sound button; the preference is saved in this browser. Forbidden clicks, occupied cells, undo and restoring a board do not play it.

Online play: random opponents and friend invites

Online play: random opponents and friend invites

When the online service is configured, guests can find a random opponent or join a friend room without accounts or nicknames. The server assigns colors. There is no free chat or public ranking.

Random matching waits up to two minutes and needs another connected player. Friend invites expire after ten minutes if nobody joins. Share the code or invite link with your intended opponent.

Both online modes use 30 seconds per move, no undo and a maximum two-hour game. Moves are final only after server validation. Confirm resignation before leaving an active game or choosing another mode. The clock keeps running during disconnects: the 60-second return grace does not extend the move limit. The same tab’s saved secret can restore a session; blocked or cleared storage may prevent return after a reload. Offline time options remain separate.

Try a different kind of board

Try Reversi and change the position by flipping opposing discs.

Play Reversi