GOMOKU Black to move. Where do you win? Each problem has one square that makes exactly five on this turn. Open the answer after you choose, or load the position and try the move.
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.
Problem 1. The closed end
Four Black stones sit on G8, H8, I8, and J8. F8 is White. One empty square finishes the row.
Answer
K8. F8 is blocked by White, so K8 is the only fifth stone. G8 through K8 is exactly five. E8 does not connect, because F8 is White.
Problem 2. The gap
Black has F8, G8, I8, and J8. One intersection inside that row is empty.
Answer
H8. Filling the gap makes F8 through J8, exactly five. K8 only lengthens the end and leaves the gap, so it does not win.
Problem 3. The diagonal
Black has G7, H8, I9, and J10. F6 is White, which closes the other end of the same diagonal.
Answer
K11. G7 through K11 is exactly five on the diagonal. J11 is beside the line, not on it, so it does not win.
Problem 4. The column
Black has I6, I7, I8, and I9. I5 is White. The winning square is the empty end of this column, not a neighbor on the side.
Answer
I10. I6 through I10 is exactly five. I5 is White, so the line does not become six. H10 is beside the column, so it does not win.
More shape explanations are on the Learn Gomoku page.