Spiral Galaxies
Spiral Galaxies is a symmetry-based logic puzzle invented by ゲサク (Gesaku) and first published in Nikoli volume 96 (2001) under the original title 天体ショー (Tentaishō), meaning “Celestial Show.” The name is a clever pun on 点対称 (Tentaishō), the Japanese term for “point symmetry.”
In this puzzle, solvers divide the grid into regions (called galaxies), each centered around a marked dot. Every galaxy must exhibit 180-degree rotational symmetry about its center, creating a pattern that feels both mathematical and aesthetic — reminiscent of celestial or spiral formations.
Outside Japan, the puzzle became known under several names, including Spiral Galaxies, Sym-A-Pix (SAP) by Conceptis, Artist’s Block (Grant Fikes), and PivotPix (Any Puzzle Media). Its elegant blend of geometric reasoning and visual harmony has made it one of the most distinctive and recognizable Nikoli puzzle types.
In this puzzle, solvers divide the grid into regions (called galaxies), each centered around a marked dot. Every galaxy must exhibit 180-degree rotational symmetry about its center, creating a pattern that feels both mathematical and aesthetic — reminiscent of celestial or spiral formations.
Outside Japan, the puzzle became known under several names, including Spiral Galaxies, Sym-A-Pix (SAP) by Conceptis, Artist’s Block (Grant Fikes), and PivotPix (Any Puzzle Media). Its elegant blend of geometric reasoning and visual harmony has made it one of the most distinctive and recognizable Nikoli puzzle types.
Rules
Divide the grid along the grid lines into connected regions – “galaxies” – with rotational symmetry. Each cell must belong to one galaxy, and each galaxy must have exactly one circle at its center of rotational symmetry.
Click to see the answer.