How to Play Spiral Galaxies
1. Read the stars
Each star sits at a grid intersection. Tap a color in the palette to choose which star's region you want to extend, then tap a cell to claim it for that star.
2. Build symmetric regions
If you tap cell A for star S, the cell that is 180ยฐ across from A (rotated about S) is also automatically assigned to S. Watch the math happen visually.
3. Cover the grid
Every cell must be claimed by exactly one star. When a region is fully symmetric and complete it glows green. When all green, you win.
4. Use hints
Stuck? Tap "Use Hint" to reveal one cell of the unique solution. With three hints per level you can still get all 3 stars.
Tips & Strategy
- Start with the most constrained star: the one with the fewest reachable cells. Its shape is forced.
- If a star sits in a corner, its region is a triangle or L-shape. If it sits in the center, it can be a long symmetric blob.
- Two stars on the same horizontal line often split the grid into two stacked rectangles โ but they can also interleave.
- Use Undo freely. Every move commits two cells (a cell and its 180ยฐ partner), so you can experiment quickly.
About the Puzzle
Spiral Galaxies (Japanese: Tentai Show, ๅคฉไฝใทใงใผ) was invented by Nikoli and is also shipped in Simon Tatham's Portable Puzzle Collection as "Galaxies". The mathematical version is NP-complete (Friedman 2012). GameZipper's 30 handcrafted levels all have exactly one solution, verified by a backtracking solver.
Related Games
If you enjoy Spiral Galaxies, try Fillomino, Nurikabe, Yajilin, and Tapa for more Nikoli-style logic puzzles.