Rules
Galaxies is a region puzzle. The board is a grid of cells. A thick frame runs around the outside and counts as a wall. Thin lines show the interior edges, which are the ones you mark. Dots sit on top. A dot may sit in the middle of a cell, halfway along an edge, or on an interior corner where four cells meet. The frame never holds a dot. You draw walls so the cells split into galaxies. Each galaxy has one dot, and a half-turn about that dot lands every cell of the galaxy on another cell of the same galaxy. A wall separates two galaxies. A wall cannot go through a dot. An × on an edge is your note that the two cells stay in the same galaxy. It is not a wall. You do not have to place every ×, and an × that is left inside a finished galaxy does not change the result. While you play, an edge you have not decided stays quiet. A clash is a wall through a dot, a closed region with no dot, a closed region with two or more dots, a closed region that is not a half-turn about its dot, or an × that is the only join between two finished galaxies. The puzzle is finished when the walls are the borders of the one set of galaxies. Play and print are 5×5, 6×6, 7×7, 8×8, 9×9, 10×10, and 6×8, each at easy, medium, and hard. The 6×8 board is 6 rows by 8 columns. The daily puzzle is a 7×7 easy grid. People also look this up as Spiral Galaxies.
- A galaxy. Each region has one dot, and a half-turn about that dot lands every cell of the region on another cell of the same region. Every cell belongs to one galaxy.
- A wall. A wall separates two galaxies. The outer frame already counts as a wall. A wall cannot go through a dot.
- An open mark. An × on an edge is your note that the two cells stay in the same galaxy. It is not a wall. You do not have to place every ×.
The picture of a finished grid draws the solved walls in teal. The frame is teal. Every cell is a soft teal. Dots stay ink. No ×. No yellow. A printed puzzle page shows the dots on a light grid, with no walls. A printed answer draws a thick line between galaxies and keeps the dots. On screen, that answer matches the print. The PDF is black and white.
- Dot
- Wall
- Open mark
- Clash
Choose Wall or Open under the board. Wall starts selected. Tap an edge to place the selected mark. Tap the same mark again to clear it. A tap with the other tool replaces the mark that is there. Right-click, or press and hold, places the other mark once. One tap is one edge. Arrow keys move the edge cursor and stop at the edge. The cursor starts on the line between the top-left cell and the cell under it. Space or Enter places a wall. X places an ×. Backspace or Deleteclears the edge. M switches Wall and Open.
Press Hint for one step the dots already force, with a sentence saying why. Hint lights the cells it uses and the dot it names, then places every edge that step decides. One press can place several walls and several × marks together, and undo takes that press back in one step. Press Check when you want the board checked. A legal unfinished board gets "No mistakes so far. Keep going!" A broken board gets "Something breaks the rules. Look for the marked edges." Hint on a broken board gets "This board has a mistake, so there is no hint yet." If Hint finds nothing on a legal board, it says "No forced edge from here. A wall may be in the wrong place, so try Check or Undo." Undo and Redo step through the marks. Reset clears every wall and every ×. When the walls match, they turn teal, the cells turn a soft teal, and the frame turns teal. Any × on the board is hidden. The dialog title is "Solved!" The dialog body is "Every cell sits in one galaxy, and each galaxy is symmetric about its dot." The line under the board is "Tap an edge to mark it. Long press or right-click for the other mark." Once the grid is solved, that line is "Every cell sits in one galaxy, and each galaxy matches a half-turn about its dot." The Mistakes counter counts how many times Check found a broken board. It is not a score.
A coral edge or a coral cell is a clash that is already on the board. With error highlighting off, none of that coral is drawn. A wall through a dot turns that edge coral. A closed region with the wrong number of dots, or a region that is not a half-turn, turns the cells coral and leaves the walls violet. An × between two finished galaxies turns that edge coral. On the picture in this article, that × also joins the two cells into one region, so the cells turn coral as well. Print pages cannot show the yellow, the coral, or the teal.
The dots
A dot already owns the cells it sits on. A cell-centre dot owns that one cell. An edge dot owns the two cells across the edge. A corner dot owns the four cells around the point. One press writes every edge those home cells already share, walls where two homes have different dots and an × where they have the same dot. The wash is every home cell. One dot turns yellow. A cell that only one dot can cover is given to that dot, and the cell across the half-turn comes with it. The button writes the edges between those new cells and the cells already placed. A blank grid in this set opens on the first sentence. Only one centre is the next press on the grid used for it. An easy grid in this set does not say only one centre. An easy label still returns that sentence when it is the next step.
The cells a dot owns Easy
A dot already owns the cells it sits on. On this blank grid the press writes six edges, and it washes every home cell. The lit dot is the centre of row 1 column 1. It is the home cell with the lowest index. The sentence names one dot. The press still writes the edges of every dot at once.
Three of the edges are walls, because the two home cells have different dots: row 1 column 1 to row 2 column 1, row 2 column 1 to row 2 column 2, and row 4 column 4 to row 4 column 5. Three are × marks, because the two home cells share a dot: row 1 column 4 to row 2 column 4, row 4 column 2 to row 5 column 2, and row 4 column 5 to row 5 column 5. Row 3 column 3 is a home cell and it is washed, and this press gives it no edge. The neighbour of a lone home cell is not written until that neighbour has an owner. No galaxy is closed yet, so no cell takes a finished tint.
The new walls and the new × marks are yellow. The other dots stay ink. The grid is still unfinished. This is the opening press on every grid in this set. The toast is "The dot already owns the cells it sits on." Every label returns this hint. It does not finish. The next press on this grid is a centre that has to be tried, and that press solves. The live button skips that toast.
Six edges the home cells already share. Yellow walls and yellow × marks. Every home cell is washed. The dot in row 1 column 1 is lit. Row 3 column 3 is washed and gains no edge.
Only one centre Easy
Some cells are not homes, and only one dot can be their centre. On this grid row 1 column 1 can only belong to the edge dot between row 1 column 2 and row 2 column 2. A half-turn about that dot lands row 1 column 1 on row 2 column 3, so both cells join. The press writes two × marks: row 1 column 1 to row 1 column 2, and row 2 column 2 to row 2 column 3. The × between row 1 column 2 and row 2 column 2 is already there, from the opening press. It stays violet.
The two new cells are washed. The edge dot turns yellow. The nine edges from the opening press stay violet. No galaxy is closed yet. The grid is still unfinished. This is not an opening. The same grid says this sentence again later. That later press is not drawn.
The toast is "Only one dot can be the centre of this cell." Every label returns this hint, including an easy label. It does not finish. An easy grid in this set never says this sentence. An easy label still returns it when it is the next step.
Row 1 column 1 has only one possible centre, so row 2 column 3 comes with it. Two yellow × marks. Those two cells are washed. The earlier home marks stay violet.
Reach
A cell that already touches one galaxy, and that no other galaxy can reach, joins that galaxy. A cell that does not touch it yet can still have only one galaxy able to reach it, and the cell across the half-turn comes with it. The button writes the edges that placement decides. A blank grid in this set does not open on either sentence. Both are early sentences, so an easy label returns them.
The cell that touches Easy
Row 1 column 3 now touches the galaxy at row 1 column 2, and no other galaxy can reach it. A half-turn about the same edge dot lands row 1 column 3 on row 2 column 1. Both cells join. The press writes four × marks: row 1 column 1 to row 2 column 1, row 1 column 2 to row 1 column 3, row 1 column 3 to row 2 column 3, and row 2 column 1 to row 2 column 2.
The two new cells are washed. The edge dot turns yellow again. The earlier walls and × marks stay violet. No galaxy is closed yet. The grid is still unfinished. This is the next press on the same grid as only one centre. It is not an opening. On many grids this sentence is the last press, and the live button skips that toast.
The toast is "This cell touches one galaxy, and no other galaxy can reach it." Every label returns this hint. It does not finish.
Row 1 column 3 touches the galaxy, so row 2 column 1 comes with it. Four yellow × marks. Those two cells are washed. Earlier marks stay violet.
Only one galaxy can reach it Easy
Row 1 column 5 does not touch the edge dot between row 3 column 4 and row 3 column 5. That dot is still the only galaxy that can reach it. A half-turn about the dot lands row 1 column 5 on row 5 column 4. Both cells join. The press writes two walls: row 1 column 5 to row 2 column 5, and row 4 column 4 to row 5 column 4.
The two new cells are washed. That edge dot turns yellow. The earlier marks, including the × between row 3 column 4 and row 3 column 5, stay violet. The two new cells do not touch the home pair. No galaxy is closed yet. The grid is still unfinished. This is the next press on the same grid. It is not an opening. A few grids finish on this sentence. The live button skips that toast.
The toast is "Only one galaxy can reach this cell. Its partner comes with it." Every label returns this hint. It does not finish.
Only the edge dot between row 3 column 4 and row 3 column 5 can reach row 1 column 5, so row 5 column 4 comes with it. Two yellow walls. Those two cells are washed. They do not touch the home pair.
One piece
A galaxy that already owns two cells which do not touch would split if the cells between them stayed out. The button gives those cells to the galaxy. The press writes walls and open marks together. It does not finish the grid. A blank easy grid never says this sentence. An easy label returns nothing when this is the next step. Medium, hard, and any other label return it.
The bridge Medium
Row 1 column 1 and row 5 column 1 already belong to the dot in row 3 column 1, from an earlier press, and they do not touch that dot. Row 2 column 1 is the cell that keeps the galaxy in one piece. A half-turn about the dot lands row 2 column 1 on row 4 column 1. The press writes four × marks and two walls: × on row 1 column 1 to row 2 column 1, row 2 column 1 to row 3 column 1, row 3 column 1 to row 4 column 1, and row 4 column 1 to row 5 column 1; walls on row 2 column 1 to row 2 column 2 and row 4 column 1 to row 4 column 2.
After the press, the whole first column is one galaxy. Row 2 column 1 and row 4 column 1 are the washed cells. Row 1 column 1, row 3 column 1, and row 5 column 1 take the finished tint of that galaxy. They are not a second hint. Two one-cell galaxies in the bottom row, row 5 column 4 and row 5 column 5, were already closed before this press. Their walls stay violet. Row 5 column 5 uses the same soft yellow as a hint wash, because finished galaxies cycle through five fills. It is not a hint cell. The new walls and the new × marks are yellow. The dot in row 3 column 1 turns yellow. The grid is still unfinished. This is not an opening.
The toast is "This galaxy would split if this cell stayed out." An easy label returns nothing. The toast for that label is "No forced edge from here. A wall may be in the wrong place, so try Check or Undo." Medium, hard, and any other label return this hint. It does not finish. The next press on this grid solves. The bridge is never the last press on a grid in this set.
Row 2 column 1 is the link that keeps the row 3 column 1 galaxy in one piece, so row 4 column 1 comes with it. Four yellow × marks and two yellow walls. Wash on those two cells. The rest of that column takes the galaxy tint.
Try a centre
More than one dot can still be the centre of a cell. The button tries the others. When each of them breaks a rule, the cell belongs to the centre that remains, and the cell across the half-turn comes with it. The picture leaves the grid unfinished. The trial is not drawn. The sentence about a cell that stays the same whichever centre you assume never writes on these grids. A blank easy grid, and a blank medium grid, never say the sentence that is drawn. An easy label and a medium label return nothing when it is the next step. A hard grid still opens on the cells a dot owns.
Every other centre Hard
Row 5 column 2 and row 5 column 6 already belong to the dot in row 5 column 4. They were placed because only that galaxy could reach them. Row 4 column 2 still has more than one dot that could be its centre. Every centre except the dot in row 5 column 4 breaks a rule. A half-turn about that dot lands row 4 column 2 on row 6 column 6. The press writes two walls and two × marks: walls on row 3 column 2 to row 4 column 2 and row 4 column 1 to row 4 column 2, and × marks on row 4 column 2 to row 5 column 2 and row 5 column 6 to row 6 column 6. All four edges touch the two new cells.
The two new cells are washed. The dot in row 5 column 4 turns yellow. The wall above row 4 column 2 also closes row 3 column 2, which is its own one-cell galaxy. That cell is not washed. It takes a finished tint. Several galaxies along the top were already closed. Four of them use the same soft yellow as a hint wash: row 1 column 4, row 1 column 5, row 2 column 1, and row 2 column 2. They are not hint cells. Their marks stay violet. The grid is still unfinished. This is not an opening. The trial is not drawn.
The same idea, that a cell comes out the same whichever centre you assume, would say "Whichever centre is assumed, these cells stay the same." That sentence never writes on these grids. It has no figure.
The toast is "Every other centre for this cell leads to a contradiction." An easy label and a medium label return nothing. Hard and any other label return this hint. It does not finish. The next press on this grid is another centre, and it solves. The live button skips that toast. Every hard grid in this set finishes on that kind of press.
Every other centre for row 4 column 2 breaks a rule, so it joins the dot in row 5 column 4, and row 6 column 6 comes with it. Two yellow walls and two yellow × marks. Those two cells are washed. Row 3 column 2 closes as its own galaxy and is not washed.
Common mistakes
Check paints a broken rule. Hint will not explain a board that is already broken. The toast is "This board has a mistake, so there is no hint yet." Check says "Something breaks the rules. Look for the marked edges." A wrong wall or a wrong × can also sit there with no coral at all. Then Check says "No mistakes so far. Keep going!" If the marks still force a step, Hint offers it. The wrong mark stays, and the new marks are the ones that turn yellow. The button does not call the hint on a broken board. The figures of a broken board do not draw yellow. A direct look at each of those boards still returns the opening step. With error highlighting off, the same clashes paint nothing coral.
Six pictures, all on the same 5×5. A wall through the edge dot paints that edge. A walled-off cell with no dot paints the cell. Two one-cell galaxies joined by one × paint both cells and that ×. A pair that is not a half-turn paints the two cells and leaves the × violet. A wrong wall on an edge the opening press does not touch stays violet after that press. A wrong × on that same edge stays violet after that press.
A wall on the edge between row 1 column 4 and row 2 column 4. That edge is the edge dot's own edge. Coral on that edge. No cell wash. No yellow.
Row 1 column 2 is closed by the frame and three walls. Coral-soft fill on that cell. The three walls stay violet. No yellow.
Row 1 column 1 and row 2 column 1 are each a one-cell galaxy about their own centre. The × between them is the only join. Coral-soft on both cells. Coral on the ×. The three walls stay violet. No yellow.
Row 1 column 1 is a cell-centre dot. The partner of row 1 column 2 about that dot is off the board. Coral-soft on both cells. The × and the three walls stay violet. No yellow.
A wall between row 1 column 2 and row 1 column 3. Before the hint the board is legal and unfinished. Check says "No mistakes so far. Keep going!" The wall is not coral. The picture is after the opening hint. The wrong wall stays violet. The six home edges are yellow. The home cells are washed. No coral.
An × between row 1 column 2 and row 1 column 3. Before the hint the board is legal and unfinished. The × is not coral. The picture is after the opening hint. The wrong × stays violet. The six home edges are yellow. The home cells are washed. No coral. Check, before or after the opening hint, says "No mistakes so far. Keep going!"
What to play next
Every grid opens on the cells a dot already owns. Easy grids then use a cell that touches one galaxy. Some easy sizes also use a cell that only one galaxy can reach. One 6×6 easy grid finishes on that sentence. The button uses a separate sentence for each of those. It does not say only one centre on an easy grid in this set, even though an easy label returns that sentence when it is the next step. It never says the bridge, and it never says a centre that has to be tried. Start on a 5×5 easy grid, or on the daily 7×7 easy grid. Medium grids add the bridge. A medium grid still opens on the cells a dot owns, and it finishes on the cell that touches. Hard grids add a centre that has to be tried. That sentence is the last press, so the live button skips the toast. A hard grid still opens on the cells a dot owns, and it can come back to an early sentence. The sentence about a cell that stays the same whichever centre you assume does not come up as its own hint. An easy label does not return the bridge or the tried centre. A medium label does not return the tried centre.
A printed puzzle page shows the dots on a light grid. A printed answer draws a thick line between galaxies and keeps the dots. Four 5×5, 6×6, or 7×7 grids share a sheet. Two 8×8, 9×9, 10×10, or 6×8 grids share a sheet. Large print is one grid on the sheet. The printable page isGalaxies packs.
- Easy5×5The cells a dot owns, then a cell that touches. One grid also uses a cell that only one galaxy can reach. All three finish on the cell that touches. They do not say only one centre, the bridge, or a tried centre. All three open on the cells a dot owns.Play 5×5 →
- Easy6×6The cells a dot owns and a cell that touches. One grid also uses a cell that only one galaxy can reach, and that grid finishes on it. The other two finish on the cell that touches. They do not say the later sentences. All three open on the cells a dot owns.Play 6×6 →
- Easy7×7The cells a dot owns and a cell that touches. Two grids also use a cell that only one galaxy can reach. One of those finishes on it. The other two finish on the cell that touches. This is the daily size. They do not say the later sentences.Play 7×7 →Today's daily →
- Easy8×8The cells a dot owns, a cell that touches, and a cell that only one galaxy can reach. All three finish on the cell that touches. They do not say the later sentences.Play 8×8 →
- Easy9×9Those three sentences. All three finish on the cell that touches. They do not say the later sentences.Play 9×9 →
- Easy10×10Those three sentences. This is the only dense size. All three finish on the cell that touches. One grid says the far cell before the cell that touches. They do not say the later sentences.Play 10×10 →
- Easy6×8The cells a dot owns and a cell that touches, on the wide grid. Two grids also use a cell that only one galaxy can reach. All three finish on the cell that touches. They do not say the later sentences.Play 6×8 →
- Medium5×5The cells a dot owns, a cell that touches, a cell that only one galaxy can reach, and the bridge. All three finish on the cell that touches. The bridge is never the finish. They do not say only one centre, and they do not say a tried centre. The bridge picture is one of these grids.Play 5×5 →
- Medium6×6Those sentences. The far cell comes before the cell that touches. All three finish on the cell that touches. They do not say a tried centre.Play 6×6 →
- Medium7×7Those sentences. All three finish on the cell that touches. They do not say a tried centre.Play 7×7 →
- Medium8×8Those sentences. The far cell comes before the cell that touches. All three finish on the cell that touches. They do not say a tried centre.Play 8×8 →
- Medium9×9Those sentences. All three finish on the cell that touches. They do not say a tried centre.Play 9×9 →
- Medium10×10Those sentences, on the dense grid. All three finish on the cell that touches. One grid says the far cell before the cell that touches. They do not say a tried centre.Play 10×10 →
- Medium6×8Those sentences, on the wide grid. All three finish on the cell that touches. One grid says the cell that touches before the far cell. They do not say a tried centre.Play 6×8 →
- Hard5×5The cells a dot owns, then a centre that has to be tried. One grid also says a cell that touches. They do not say the far cell, only one centre, or the bridge. All three finish on the tried centre. The home picture and the mistake pictures are one of these grids.Play 5×5 →
- Hard6×6The cells a dot owns, a cell that touches, a cell that only one galaxy can reach, and a tried centre. One grid also says only one centre. They do not say the bridge. All three finish on the tried centre. The only-one-centre picture, the touch picture, the far-cell picture, and the tried-centre picture are two of these grids.Play 6×6 →
- Hard7×7Those sentences, and one grid also says the bridge. They do not say only one centre. All three finish on the tried centre. One of them opens on a six-edge home press. The article uses the 5×5 home instead.Play 7×7 →
- Hard8×8The cells a dot owns and a tried centre. Two grids also say a cell that touches and a cell that only one galaxy can reach. One grid says nothing between the opening and the tried centre. They do not say the bridge or only one centre. All three finish on the tried centre.Play 8×8 →
- Hard9×9The cells a dot owns, a cell that touches, a cell that only one galaxy can reach, and a tried centre. One grid also says only one centre, after a cell that touches. One grid also says the bridge. All three finish on the tried centre.Play 9×9 →
- Hard10×10Those sentences, on the dense grid. Two grids also say the bridge. They do not say only one centre. All three finish on the tried centre. One of those last presses writes a large set of edges.Play 10×10 →
- Hard6×8The cells a dot owns, a cell that only one galaxy can reach, a cell that touches, and a tried centre, on the wide grid. One grid also says the bridge. They do not say only one centre. All three finish on the tried centre.Play 6×8 →
There is no guide-sized seed to open. The boards above are teaching boards.