What is the galaxies puzzle?
The galaxies puzzle asks you to cut a grid into pieces. Each piece must contain exactly one dot, and the dot must be its exact centre: spin the piece half a turn around the dot and it lands on itself. When every square belongs to a symmetric piece, the puzzle is solved.
Nothing to count, no numbers, just shapes and symmetry. Play the galaxies puzzle online free here, with spiral galaxies boards from 7×7 to 15×15.
Where Spiral Galaxies comes from
The puzzle was invented by Nikoli, the Japanese puzzle publisher, under the name Tentai Show. In English it is usually called Spiral Galaxies, because the finished shapes often curl around their dots like galaxies around their centres. You may also see it called the galaxy puzzle.
How to play here
Pick a size and level on the start card, then press Play. Click or tap a grid line between two squares to draw a wall, and click it again to remove it. A region turns highlighted as soon as it is complete and correct.
If you know a square belongs to a dot but aren’t sure about the walls yet, you can leave yourself a reminder arrow. With a mouse, right-click a dot and drag the arrow into a square. On a phone, turn on Mark in the dock and drag from the dot. Drag an arrow off the grid to throw it away.
Undo, Redo and New puzzle are in the dock. The pause menu has Restart, Solve and Enter game ID.
How 180° symmetry works
Picture a pin through the dot and the region turning around it like a wheel. After half a turn, every square of the region must land on another square of the same region. That is why a dot in the middle of a square can own a single square, a 3×1 bar or a plus shape, while a dot on an edge needs an even number of squares, and a dot on a corner owns at least the 2×2 block around it.
This gives you a quick check: for any square you think belongs to a dot, find its partner on the far side. If that partner is off the grid or already taken by another dot, the first square can’t belong to that dot either.
A step-by-step way to solve
- Claim the fixed cores. Dots on edges and corners own their two or four squares straight away.
- Wall off neighboring dots. Two dots in adjacent squares need a wall between them.
- Mirror as you go. Every square you add to a region adds its partner on the opposite side of the dot.
- Find squares with one owner. An empty square that only one dot can reach, with its mirror square still free, belongs to that dot.
Why play Galaxies?
Galaxies feels different from most logic puzzles: you’re reasoning about shapes and balance, not numbers. The finished grid often looks like a small piece of art. If you enjoy it, try Shikaku, another puzzle about cutting a grid into regions, or Fillomino.
How to play Galaxies
- The grid is sprinkled with dots. A dot can sit in the middle of a square, on the edge between two squares, or on a corner where four squares meet.
- Divide the whole grid into regions so that each region holds exactly one dot.
- Every region must have 180° rotational symmetry around its dot. Turn it upside down around the dot and it covers exactly the same squares.
- Regions are made of whole squares joined side by side, and every square belongs to one region.
Galaxies tips
Mirror every square
If a square belongs to a dot, the square directly opposite it through the dot belongs to the same dot. Each deduction you make gives you a second one for free.
Start with dots on edges and corners
A dot on the line between two squares owns both of them. A dot on a corner owns all four squares around it. Draw those small cores first.
Wall off squares between different dots
When two neighboring squares belong to different dots, a wall runs between them. Drawing it at once keeps the board readable.
Frequently asked questions
What is Tentai Show?
Tentai Show is the original Japanese name of the puzzle, from the publisher Nikoli. In English it's usually called Spiral Galaxies, or simply Galaxies.
Does each galaxy have to look like a spiral?
No. Any shape works as long as it looks the same after a half turn around its dot. A plain rectangle or a single square is a valid galaxy.
Why do some regions change color?
The game highlights a region as soon as it is closed, holds exactly one dot, is symmetric around that dot, and has no stray walls inside. The puzzle is solved when the whole grid is highlighted.
