Rules
Star Battle is played on a grid split into regions. You place stars. You also mark cells that cannot hold one. People also call this puzzle Two Not Touch, and sometimes Stars. The count is the same in every row, every column and every region, and it depends on the size.
5×5 · one star in every row, column and region
8×8 · two stars in every row, column and region
- One count everywhere. Every row, every column and every region ends with the same number of stars. The number depends on the size.
- No touching. Two stars cannot sit next to each other, not even on a diagonal. One step in any direction is too close.
- One solution. The grid has exactly one finished placement. You can reach it by the checks below. You never need to guess.
The count is fixed for the size. A 5×5 takes 1 star in every row, column and region. 8×8 and 10×10 grids take 2 stars in every row, column and region. Regions are the tinted areas. Each one is a single connected piece, and each one takes the same number of stars as a row.
Touching means a king’s move in chess: any of the eight cells around a star, edges and corners alike. Marks are only pencil. They are not part of the solution, and two marks may sit side by side.
First moves Easy · one star
On a one-star grid, Easy falls to two ideas. A cell that touches a star is empty, and a unit’s quota forces the last star or clears the cells that are left. On PuzzleKite, Easy stops before it searches across units. Two-star grids add pair packing. That is the next section.
The one-star figures use a Hard 5×5, so the boards below already carry marks from later sections. The highlighted cells are what the Easy checks find next.
Adjacency Easy
The moment a star is placed, mark every open cell a king’s move away. Those cells cannot be stars, and leaving them blank hides the next count.
The star’s cells above and the cell to its right were already marked. Four neighbours are still open: the cell to its left, and the three cells just under it. Mark all four.
Rows and columns Easy
Count what a line still needs against the cells it still has. If the open cells are exactly the stars it needs, those cells are stars, as long as they do not touch each other. If the line already has its stars, every open cell on it is empty.
Four cells of column 1 are marked. One cell is open, at the bottom, and the column still needs its star. That cell is the star.
Row 5 has its star in column 1. The cell beside it was marked because it touches that star. The other three cells cannot be stars, so mark them too.
Regions Easy
A region is counted the same way as a row. There is a second easy case: when every cell a region can still use sits in one row or one column, and the region still needs as many stars as that line does, the rest of the line is empty. That is confinement. It is still a region count, not a search across the board.
One step earlier, the top-right region’s remaining cells both sat in row 1. The region still needed its star and the row needed one, so confinement marked column 3. Columns 1 and 2 of that row were already marked. Region 1, ringed, then has a single open cell. Its star goes in row 2, column 2.
Two-star boards Easy
Most Star Battle boards are 8×8 or 10×10. Each row, column and region takes two stars, not one. The checks in section 2 still apply. Pair packing is the check a one-star grid never needs.
The figures in this section, apart from the mark-only pair, are an Easy 8×8. You can open that grid and follow Hint from the start. It finishes without a cross-unit search.
Why two stars change the board Easy
Two stars in the same row, column or region still cannot touch, so they need at least one cell between them. A unit is finished when it holds two. A third star in that unit is too many, even when the three do not touch. When the open cells left are exactly the stars still needed, and those cells do not touch, every one of them is a star. When the unit already has its two, every open cell on it is empty.
Pair packing is the step in between. The unit still needs two stars, and it has more open cells than that. Look at the pairs that do not touch. A cell in no such pair is empty. A cell in every such pair is a star. Hint files this under process of elimination. The layer is local: the check stays inside one unit.
Pair packing Easy
On the Easy 8×8, row 2 still needs two stars and has three open cells in a row. The ends do not touch. The middle touches both ends, so it is in no legal pair. The ends are in the only legal pair, so both are stars. Hint places the left-hand star first.
The yellow cell is the star Hint places. The right-hand end is the other half of the only legal pair, and the middle is in no legal pair. Hint places the star first. The next mark is the middle, by adjacency, because it now touches that star. The right-hand star follows as a row count.
Sometimes no star is forced. A cell can sit in no legal pair while the other cells still pair in more than one way. Hint then marks that cell and leaves the stars for later. The Easy walk above never stops on that mark, because the squeezed cell arrives together with a star, and Hint places the star first. This Medium 8×8 shows the mark on its own. You can open that grid too.
The ringed region still needs two stars. The centre of row 2 touches every other open cell in the region, so it cannot be one of those two. The cell directly under it belongs to a different region, so it is not a partner. Other pairs inside the ring are still possible, so no star is placed yet. Hint marks the centre. The same pass marks squeezed cells in other regions too. This window shows only the one in the ringed region.
Counting with two Easy
Counting is the same idea as on a 5×5, with two in the quota. If the open cells are exactly the stars the unit still needs, and they do not touch, those cells are stars. If the unit already has two, the open cells are empty.
Row 5 has two open cells, column 1 and column 3, with a marked cell between them. They do not touch, and the row still needs two stars, so both are stars. Hint places column 1. The next mark is the cell under that star, by adjacency. Column 3 is the same row count, and Hint places it after that mark.
Row 7 has stars in column 1 and column 3. That is the whole quota. The four open cells on the right are empty, and Hint marks all four.
Confinement Easy
Confinement is still a region count. When every cell a region can still use sits in one row or one column, and the region still needs as many stars as that line does, the rest of the line is empty. On a two-star grid the region needs two, so it claims the whole line. On this Easy 8×8 that is the opening mark, before the pair packing above.
The three-cell region in the middle of row 1 still needs two stars, and row 1 needs two, so every cell of that row outside the region is empty. The three-cell region down column 1 forces the same corner: that column also needs two, and the region already claims both. Hint marks row 1, column 1. It does not, in this one step, mark the rest of either line.
Looking across units Medium
Medium grids need one more question. Could this cell be a star without leaving some other row, column or region unable to take its stars? If every way of using the cell wipes another unit out, the cell is empty. If every way of filling its unit uses the cell, the cell is a star. Hint still calls this process of elimination. The new part is the cross-unit check.
The open cell in row 2, column 4 touches all three cells of the top-right region. A star there leaves that region with nowhere to go. Mark it. Nothing else is on the board yet: this is the first move, even though the Easy section comes first in the guide.
The same check covers a whole unit, not only one cell. On a two-star grid it tries every pair that does not touch. After the neighbouring cells are blocked, every other row, column and region must still be able to reach its count. A cell in no surviving pair is empty. A cell in every surviving pair is a star. Pair packing, in the section above, is the same question asked inside one unit only.
The 5×5 above is the worked example, because one cell wipes out a whole region. On the Medium 8×8 from the pair-packing mark, Hint does place a cross-unit star, but only after other pairs have already been ruled out. A crop of that cell would not show why. The check is the one this section describes.
Process of elimination Hard
Hard grids add a one-cell what-if. Pick an open cell. Assume it is a star and run the Medium checks. Assume it is a mark and run them again. If the star breaks the board and the mark does not, the cell is empty. If only the mark breaks, the cell is a star. Hint files this under process of elimination too. The difference is the contradiction. The same what-if works on a two-star board. The 5×5 is the clearest place to see it fail.
Three marks are already settled: row 2 column 4, row 4 column 1, and row 4 column 4. The corner in row 1 is still open, and no count or cross-unit check forces it yet. Try it both ways.
Medium checks then leave row 4 with three open cells, and none of them can be its star.
An X there does not break the board. The corner is empty.
The failing check is not a simple shortage. A star in the corner lets the Medium checks run, and they leave row 4 with three open cells, columns 2, 3 and 5. None of those three can be the row’s star. The mark in the corner does not cause that break, so the corner stays empty. The rings on the second board are those three cells.
Common mistakes
Each of these breaks one rule and leaves the others alone. The first three are on the 5×5, where each unit gets one star. The last is on the 8×8, where the row already has its two. Check catches all four.
Touching on a corner
These two stars do not share a side, but they share a corner. That still counts.
Two stars in one region
On this 5×5 the region only gets one star. These two do not touch, and the region still has one too many.
Two stars in one row
On this 5×5 the row only gets one star. These two do not touch, and the row still has one too many.
Three stars in one row
On this 8×8 the row already has its two, and they do not touch. A third star is one too many.
Next steps
The cards below are the technique ladder. Easy and Medium open on 8×8 (two stars), where most puzzles live. Hard opens the guide’s 5×5, where the one-cell what-if is easiest to see. The size changes the quota, not the order of the checks.
- EasyAdjacency and countsTouching cells, pair packing, and units that are full or down to their last stars. No cross-unit search.Play 8×8 Easy →
- MediumAdd cross-unit checksA candidate has to leave every other row, column and region able to take its stars.Play 8×8 Medium →
- HardAdd one-cell contradictionsAssume a star or a mark, run the Medium checks, and drop the choice that breaks. Clearest on a small board.Play Hard 5×5 →
Today’s daily is a 5×5 Easy, one star per line. The main path after that is 8×8 Easy, then 10×10 Easy. Both place two stars in every row, column and region, and both use the pair packing in section 3. The Hard 5×5 in the one-star figures is an optional deep dive: open it when you want the cross-unit mark and the one-cell what-if on a small board. Open the Easy 8×8 from section 3.