What is Goishi Hiroi?

Goishi Hiroi (碁石拾い, literally "Go Stone Picking") is a traditional Japanese topological logic puzzle popularized by Nikoli. Players start at Stone #1 and must pick up all stones on the board by moving in orthogonal lines, turning 90 degrees at every collected stone, without jumping over uncollected stones.

Can I jump over stones in Goishi Hiroi?

You cannot jump over uncollected stones — they block your line of sight. However, once a stone has been collected and removed, subsequent paths can pass freely through that grid intersection.

Can you go straight through a stone?

No. The strict rule of Goishi Hiroi is that you must make a 90-degree turn (left or right) at each picked stone until the final stone is reached.

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Goishi Hiroi

Easy

Pick up all Go stones in sequence, turning 90° at each stone!

STONES:0 / 8

TIME:0:00

Turn 90° At Each Stone

Mastering Goishi Hiroi: Japanese Stone-Picking Strategy

Dating back hundreds of years in Japanese culture and modernized by Nikoli,Goishi Hiroi is a pure test of foresight, parity, and topological geometry.

Rules of the Stone Master

Mandatory 90° Turn: Every step alternates between horizontal and vertical travel. If step \(k\) moved vertically, step \(k+1\) must move horizontally.
Line-of-Sight Visibility: From any stone, you can only pick the very first stone visible in a legal perpendicular direction. Any stone further down the line is blocked until the closer stone is removed.
Total Cleansing: The puzzle is only solved when every single stone has been collected into a single chain of length \(N\).

Key Deduction Insights

Look for “dead-end” stones located on outer rim coordinates that have only a single stone in their perpendicular rank or file. Such stones often must either be the final stone of the puzzle or must be visited at a precise moment when their sole exit is still uncollected. If picking stone A strands stone B with no valid entry angle, stone A must be delayed!