Tentai Show

Tentai Show is a binary determination logic puzzle published by the Japanese puzzle company Nikoli, also known in English by the names Tentaisho, Galaxies, Spiral Galaxies and Sym-a-Pix. It is played on a rectangular grid containing a number of dots, or stars, and the solver must divide the entire grid into regions called galaxies so that every galaxy has exactly one dot at its center and is symmetric under a 180 degree rotation about that dot. The dots are sometimes colored, and coloring the finished regions to match their dot can reveal a simple picture, though the coloring itself has no bearing on the logical solution. The puzzle's Japanese name plays on two readings, combining the word for dot with the word for symmetry, a pairing that also evokes the Japanese word for astronomical body, matching the puzzle's visual result of dot centered galaxy shaped regions across the grid.