How to play
Tentai Show — 天体ショー — or Spiral Galaxies is a symmetry puzzle.
- Divide the whole grid into regions called galaxies. Every cell belongs to exactly one.
- Each galaxy is a single connected piece — you can walk between any two of its cells without leaving it.
- Each galaxy contains exactly one dot, and that dot is its centre of symmetry. Turn the galaxy half a turn about its dot and it lands on itself.
- A dot in the middle of a cell, on the line between two cells, or on a corner where four meet — all three are allowed, and each tells you something about the shape.
Tap a dot to choose its galaxy, then tap the cells you think belong to it. Each cell you claim pulls in its opposite number about the dot, so the board only ever shows symmetric galaxies. Tap a cell of the chosen galaxy again to hand it back.
On the name
Tentai Show is published in English as Spiral Galaxies. The name puns on ten (dot) and taishō (symmetry), and written 天体ショー it also reads as "astronomical show".
The rules in full