The 26 openings: what the first three stones decide

How the twenty-six are counted

Move 1, Black, goes on the center point of the board.

Move 2, White, goes inside the 3×3 around the center. Fold the rotations and reflections together and only two shapes survive — attaching orthogonally, the direct opening, or attaching diagonally, the indirect one.

Move 3, Black, goes inside the 5×5 centered on the same point.

Fold the third move's squares by symmetry within each of those two shapes and thirteen remain in each. 13 + 13 is twenty-six: the 26 openings.

The rule behind star and moon

Japanese Renju players named them, and one rule sorts every name — if moves 1 and 3 sit on the same line or diagonal with exactly one empty point between them, the opening is a star; everything else is a moon.

That is why Kagetsu and Hogetsu are moons while Kansei and Sosei are stars. The last part of the name already tells you whether the third stone lined itself up with the first.

All twenty-six names

Thirteen direct and thirteen indirect. The numbering follows the international Renju notation, D1–D13 and I1–I13.

This page covers how the openings are classified and named. The exact third-move square of each one, and the book lines that follow, belong to specialist Renju material and are not reproduced here.

Openings work differently under freestyle

These names come from Renju, which restricts Black with forbidden moves and, in tournaments, adds a further rule per opening to balance it — offering two choices for the fifth move, for instance.

Freestyle in Gomoku Mate has no such device, so Black’s opening advantage is larger here than in Renju. To play with the forbidden rules and the opening regulation, pick Renju or Renju · official opening in the game rules. Renju · official opening applies the tournament balance in full: the centered first three stones, White’s color swap, and a fifth move Black offers as two squares for White to choose from.

The opening the Gomoku world championships have used since 2009 is ‘Swap2’. One player places two black stones and one white stone anywhere; the other reads the position and either keeps White, takes Black, or adds one stone of each color and hands the choice of color back. It brings the first player's win rate down to around 52 percent, so it rewards judging a position rather than memorizing an opening name. In Gomoku Mate you can play it as ‘Gomoku · Swap2’: no forbidden moves, and only exactly five wins.

So in a real game three things come before memorizing names: play near the center, keep your own stones connected, and on every move, check whether the opponent can make a three or a four.