Questions
Tentai Show — 天体ショー — or Spiral Galaxies is a symmetry puzzle.
- What is Tentai Show?
- Tentai Show is a Japanese logic puzzle published by Nikoli, sold in English as Spiral Galaxies. You divide the grid into regions called galaxies. Each galaxy holds exactly one dot, and the dot is its centre of symmetry: turn the galaxy half a turn about the dot and it lands back on itself.
- Why is it called Tentai Show?
- The name is a pun. Ten (点) is a dot and taishō (対称) is symmetry, so tentaishō reads as "dot symmetry". Written 天体ショー it also reads as "astronomical show", which is where the galaxies come from.
- What do the different dot positions mean?
- A dot in the middle of a cell means that cell is the exact centre of its galaxy, so the galaxy has odd width and odd height. A dot on the line between two cells means the galaxy is even in that direction. A dot on a corner where four cells meet means it is even in both. Reading the dots this way tells you a lot before you place a single region.
- Do the dot colours mean anything?
- No. Where puzzles print dots in different colours it is decoration to make regions easier to tell apart. Every dot behaves identically.
- What is the standard opening move?
- Two dots in orthogonally adjacent cells must belong to different galaxies, so the boundary between them is fixed straight away. Beyond that, each cell you assign forces its opposite number about the dot, so progress comes in pairs.
- Can a galaxy be a single cell?
- Yes. A dot in the centre of a cell with no room to grow is a perfectly good one-cell galaxy. Sizes run from one cell upwards.
- Is there always exactly one answer?
- Yes. Every puzzle here is checked by solver before it is banked, and only puzzles with a single answer reachable by reasoning are kept.
- Do I need an account?
- No. Nothing to sign up for, nothing to install. Your progress is kept in your own browser.