GOMOKU / SITE INFORMATION

Five Mistakes Beginners Make

By Gomoku Live · Published 2026-10-02 · Updated 2026-10-02

These five mistakes are about the move in front of you, not about memorizing an opening. Each pair uses the same rules as the live game: exactly five stones win, and a line of six does not.

Practice this opens the position on the play page with you as Black against the computer. The computer answers after your move. Diagrams are drawn for this page; row numbers and column letters match the 15 by 15 board. If you still have an unfinished online match in this browser, the site keeps that match instead of loading the lesson.

1. Building your own line while the opponent can win

White has four stones on row 8, from G8 through J8. F8 is already Black, so White’s only winning square is K8. Black also has three stones on row 10. The tempting move is J10, which makes a four of your own. That four is not a win yet, and it leaves K8 empty.

Bad move: the red ring is J10. It lengthens Black’s row and ignores K8.

Better move: the green ring is K8. White’s four is stopped, and Black still has the row on 10.

What happens next: if Black plays J10, White plays K8 and the row G8–K8 is exactly five. The game ends. If Black plays K8, White has no fifth stone there, and Black can keep building.

Practice this

2. Watching rows and missing the diagonal

White’s stones on G7, H8, I9, and J10 are one diagonal. F6 is already Black, so the only winning square is K11. A horizontal three on row 11, from G11 to I11, asks for J11. J11 is not on the diagonal.

Bad move: J11. Black’s row becomes four, but White’s diagonal is still open at K11.

Better move: K11. The diagonal is closed on both ends, F6 and K11.

What happens next: J11 does not win. White then plays K11, and G7–K11 is exactly five on the diagonal. K11 prevents that line.

Practice this

3. Playing beside a broken line instead of in the gap

Black already has F8, G8, I8, and J8. H8 is empty. That gap is the whole line. K8, just past J8, looks close. It does not fill the hole, so it is not five.

Bad move: K8. The gap at H8 is still empty, so this is not a winning line.

Better move: H8. F8 through J8 becomes exactly five.

What happens next: H8 wins at once. K8 does not, and White is still in the game. Count the empty point inside the line before you extend the end.

Practice this

4. Adding a stone to a line that cannot grow

On row 7, G7, H7, and I7 are Black, but F7 and J7 are White. That line cannot become five. H6, just above it, does not open either blocked end. On row 10, G10, H10, and I10 are an open three. J10 extends it.

Bad move: H6. The row on 7 is blocked at both ends, and H6 does not start a new threat.

Better move: J10. Black gets four stones with F10 and K10 still empty.

What happens next: J10 is not an immediate win. It is an open four, so White has to answer one of the ends. H6 does not force anything. Prefer a line that still has an empty end.

Practice this

5. Blocking an open four one move too late

An open four has empty intersections at both ends. One defensive stone can cover only one of them. The position below is already too late: White has G8 through J8, with F8 and K8 empty. Blocking F8 leaves K8. Blocking K8 leaves F8.

Too late: both red rings are winning squares for White. One Black stone cannot cover both.

The better moment is one move earlier, when White has only an open three on G8, H8, and I8. Taking either empty end, F8 or J8, stops that three from becoming an open four.

In time: either brown ring, F8 or J8, is a useful defense. The practice button uses F8 as the example square, but J8 works too.

What happens next: in the first diagram, a block on only one end loses on the other end. In the second diagram, F8 (or J8) keeps White from having two winning squares at once.

Practice the earlier defense

The rules page still has the short version of turns, timers, and matchmaking. This page is only the five mistakes.