Free Five in a Row (Gomoku) | Two Players or Against the Computer

How it works

Choose Two players to play a friend on the same screen, or play against the computer and pick how well it plays. Computer against computer lets you watch it play itself.
Click a point where two lines cross to place a stone. Black moves first, and the players take turns.
Get five stones in an unbroken line, across, down, or diagonally, before the other player does. Then save a PNG of the board.

How to play

The board is a grid of 15 by 15 lines, and the stones go on the points where the lines cross, not in the squares. Black moves first, then the players take turns, one stone per turn, and a stone never moves. The first to make an unbroken line of five, across, down, or diagonally, wins. Board switches to 13×13 or to the 19×19 of a Go board. Rules decides whether a line of six or more counts: Five or more wins, as in freestyle Gomoku, or Exactly five wins, as in standard Gomoku. Crosses and circles under Colors draws the game as on paper, with an X or an O in each square instead of stones on the points.

Threats and forced wins

A four, four stones in a line with room for a fifth, must be blocked at once. An open three, three in a line with both ends free, must be blocked too, or it grows into an open four, which has two ends to finish and cannot be stopped. Strong players win by making two threats with one stone: a four and an open three, or two fours. The other player can block only one of them.

How the computer plays

For every empty point it looks at the lines of five points that pass through it. A line that holds stones of only one color is worth more the more stones it holds, so the same score counts what a stone builds and what it blocks. Easy plays one of its best few points, and Medium plays the best one. Hard wins or blocks a five at once, searches for a forced win made of fours, and otherwise tries its best points against your best replies and plays the one that leaves it best placed.

Computer against computer

Choose Computer against computer under Players to watch the computer play both Black and White at the level you pick. Speed sets how quickly it moves, and the score counts Black's wins, the draws, and White's wins. Pause halts the game, and Undo steps back a move at a time. On Medium and Hard, Black wins most games: moving first is a big advantage.

Frequently asked questions

Is five in a row the same as Gomoku and Renju?

Five in a row is Gomoku. Freestyle Gomoku lets a line of six or more win, and standard Gomoku counts exactly five. Renju is a variant for experts that forbids Black some moves, such as making two open threes at once, to make up for Black's first-move advantage. This app plays freestyle or standard Gomoku, not Renju.

Does the first player have an advantage?

A big one. In 1993, a computer search by Victor Allis showed that on a 15×15 board Black, who moves first, can always force a win. That is why Renju restricts Black, and why Take turns lets you and the computer start in turn.

How do I play with a friend?

Choose Two players. You take turns at the same screen, Black first, and the score counts Black's wins, White's wins, and the draws. Undo takes back the last stone.

What do Undo and Hint do?

Against the computer, Undo takes back your last stone together with the computer's answer, and Redo plays them again. Hint highlights the point Hard would choose for the player to move.

Does this upload anything?

No. The game runs in your browser, and the board is drawn on a canvas. Save downloads a PNG. Edit opens that image in the PictorX editor.