Go rules

Go is played by two players, Black and White, on the intersections of a grid. Black plays first; each player places one stone per turn, and it never moves. The goal is to surround more territory than the opponent.

Liberties and captures

The empty intersections next to a stone, or to a group of stones joined along the lines, are its liberties. A group with none left is captured and removed from the board: its stones become prisoners. You may not place a stone that would have no liberty, unless it captures.

Ko

When a stone has just captured a single stone, the opponent may not take it back at once: they must play elsewhere first, or the same position would repeat forever.

End of the game

When both players pass one after the other, the game stops. Stones that could not escape capture are declared dead: they are removed and counted as prisoners. Each player then counts the intersections they surround plus their prisoners; White adds the komi, 6.5 points, which makes up for the advantage of playing first.

The count

The proposed dead stones are faded and a small square shows who owns each intersection. If you disagree, tap a group to mark it dead or alive, or resume the game to settle it on the board.

Hint

When in doubt, the Hint button shows on the board the move the AI would play in your place, circled in indigo, and says why: a capture, a group to save, an empty corner… You are still free to play elsewhere.

Against the AI

You play Black, the AI plays White. Easy: it picks among plausible moves. Normal: it plays the best move by its rules of thumb. Strong: it simulates thousands of game endings for each candidate move and keeps the one that wins most often. You can also resign at any time.