Galaxies
Find a symmetric galaxy around every dot
Click a grid edge to draw or erase it. Right-drag a dot or arrow to place a mirrored note; drop outside to erase. Arrow keys move between cells; Ctrl or ⌘ + arrow toggles an edge. Enter picks up or places an arrow; Delete erases it, Escape cancels. Ctrl or ⌘ Z undoes; Shift Z redoes.
Selected cell details appear when the puzzle loads.
Progress saves on this device.
How to play
Divide the grid into connected regions, each with exactly one dot at its centre. Every region must look the same after a half turn (180° rotation). Draw only the boundaries between different regions; extra lines inside a region make it invalid.
Valid galaxies shade automatically and gain ✓ marks. Dots may sit inside a square, on an edge, or at a corner. Dot numbers identify them for arrow notes; they are labels, not puzzle clues. Filled and hollow dots have the same rules.
Arrow notes say which dot a square belongs to. The upstream engine also marks its opposite square. Select a dot from “Arrow points to”, then tap a square in notes mode or press Place arrow. Drag an existing arrow to move it. Notes alone do not complete the puzzle.
Solve reveals the upstream solution and does not count as a win. Undo restores your previous work. Restart returns this puzzle to its starting position and can be undone.
Puzzle by Nikoli (Tentai Show). Engine: Simon Tatham’s Galaxies, contributed by James Harvey. MIT license and credits.