2026-08-18 · history
Hashiwokakero (1990) — Thirty-Six Years of Logic Grown from Numbers Joined by Lines
In 1990, Hashiwokakero debuted in Puzzle Communication Nikoli #31. Its rule — connect numbered islands with bridges until everything forms one network — grew out of an earlier prototype, "Ketsugoshu," that the same contributor "renin" had published in issue #28 the year before. In 2009 it was proven NP-complete; in 2004 it reached Simon Tatham's Portable Puzzle Collection ahead of any Steam release; and in 2023 Nikoli itself ported it to Switch, PC, and Xbox. This article verifies a 36-year lineage.
