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How to solve Star Battle puzzles

The fourteen ideas Stelline's hint ladder and lessons use, each on a real board, in the order a solver tries them.

The rules in one paragraph

A Star Battle-style board is a square grid cut into as many regions as it has rows. Place one queen (or, in 2 stars mode, two stars) in every row, every column and every region, and never let two pieces touch, not even at a corner. Every Stelline board has exactly one solution, and the game checks that before showing it. The full rules and controls are on the support page.

Solving is a matter of ruling cells out. A dot marks a cell that cannot hold a piece; when a row, column or region is left with exactly as many free cells as pieces it still needs, those cells are the pieces. Every idea below is a way of finding dots sooner. The names are the ones the app's hint ladder uses, and each has a lesson under Learn in the app, played on a real board, with practice positions keyed on that one idea.

the pattern the idea reads   a cell already ruled out   a cell the idea rules out   the piece it proves

Two habits before any technique

• Star neighbours. The eight cells around a placed queen or star can’t hold another one.
• Finished row, column or region. This row, column or region already has all its queens or stars, so its other cells are out.

The app can make both kinds of dots for you (Auto-dots in Settings, on by default), so the ideas below start where those two leave off.

Techniques

Ten ideas, in the order the hint ladder tries them: each one is tried only when the ones before it find nothing. They settle every Easy, Medium and Hard board in both modes.

Last cells

The highlighted row, column or region has exactly as many free cells as queens it still needs, so every one of them is a queen. Place it.

In the hint ladder: “Only as many cells are left here as queens or stars still needed, so they must all be filled.”

Nosy neighbours

The highlighted region still needs two stars. A star on a cell that touches all its other free cells would leave no room for the second. Dot that cell.

In the hint ladder: “This cell touches every place where the unit’s queen or star could still go, so it can’t hold one itself.”

Line lock

The highlighted region’s free cells all lie in one row or column, so its queen is that line’s queen. Dot the line’s other cells.

In the hint ladder: “This region fits inside one row or column and takes that line’s queen or star, so the rest of the line is out.” The reverse works too, and the hint calls it Line lock (reverse): “All of this line’s remaining cells lie in one region, so that region’s other cells are out.”

Two-by-two blocks

The highlighted region needs two stars, and its free cells form two groups that each fit in a 2×2 block: one star per group. Dot every cell that touches a whole group.

In the hint ladder: “This unit needs two stars and its cells split into two pieces that each fit a 2×2 block, so each piece holds exactly one; cells touching a whole piece are out.”

Exclusion

One cell of the highlighted region cannot hold a queen: a queen there would leave another row, column or region without room for its own. Find it and dot it.

In the hint ladder: “A queen or star here would leave a row, column or region without room for its own.”

Clumps

The highlighted region’s free cells form separate clumps, and each clump holds one star at most. With as many clumps as stars still needed, one of them has a single way to take its star. Place it.

In the hint ladder: “Split the highlighted region’s free cells into groups that each hold one star at most. With as many groups as stars still needed, a group with a single way left is forced, and the cells no placement uses are out.”

Container consumption

All of the highlighted region’s free cells lie inside one row or column that needs one star more, so the rest of that line holds exactly one star. Dot the cells that rules out and place the star it forces.

In the hint ladder: “Every free cell of this line sits inside one region that needs one star more (or the reverse). That region’s other cells hold exactly one star: dot what that rules out, place what it forces.”

Counting rows and regions

Count the regions whose free cells share the same rows: as many regions as rows means those rows’ queens are theirs. The highlighted cells lie in those rows but outside those regions. Dot them.

In the hint ladder: “Count the regions whose free cells share the same rows: as many regions as rows means those rows' queens are theirs. The highlighted cells sit in those rows but outside those regions: dot them.”

X-wing

Two rows keep their free cells in the same two columns (or two columns in two rows), so those columns’ stars belong to those rows. Dot the columns’ cells outside those rows.

In the hint ladder: “Two rows keep their remaining cells in the same two columns (or the reverse), so those columns' other cells are out.”

Finned count

Count the stars a group of rows, columns or regions still needs against the cells left for them: a star on a highlighted cell would leave that group short. Dot the highlighted cells.

In the hint ladder: “Count the queens or stars a group of rows, columns or regions still needs against the cells left for them: one placed here would leave that group short, so this cell is out.”

Advanced

Three counting ideas that look at several rows, columns or regions at once, then the last resort. Expert boards need at least one of them.

Squeeze

Take the highlighted line together with its neighbour: their free cells split into 2×2 pieces, exactly as many as the stars the two lines still need, so each piece holds one star. Dot the cells a piece’s star would always touch, and place the star of a piece with one cell left.

In the hint ladder: “Take two neighbouring rows or columns together and split their free cells into 2×2 pieces: there are exactly as many pieces as stars to place, so each piece holds exactly one.”

Set difference

Some rows, columns or regions keep all their free cells inside other units that need one star more. Take the first ones out: the cells left over, highlighted here, hold exactly one star. Dot the cells it would touch whichever of them it takes, and place it where one cell is left.

In the hint ladder: “Some rows, columns or regions keep their free cells inside other units that need one star more. Take the first out of the second: the cells left over, highlighted here, hold exactly one star.”

Fish

Three or more rows keep their free cells within as many columns (or columns within rows), so those columns’ queens belong to those rows. Dot the columns’ cells outside those rows.

In the hint ladder: “Find rows whose remaining cells all sit in just as many columns (or columns in rows): those columns' queens or stars must land in these rows, so the columns' other cells are out.”

What-if step

The what-if step is the last resort: suppose a cell, follow the forced moves, and a contradiction rules it out. In the app, the what-if lesson has you place the supposed star, follow the stars it forces until a row, column or region is starved or two stars touch, then dot the cell on a fresh copy of the board. The What-if marks setting (version 1.6) gives you the same tool on any board: the marks of a branch are drawn hollow, Keep makes them firm, Drop removes them in one step.

In the hint ladder: “A queen or star here would lead to a contradiction, so the cell is out.” The mirror image exists too: “Leaving this cell empty would lead to a contradiction, so it must hold a queen or star.”

Common two-star shapes

Each drawing is a region that needs two stars (one for the 2×2 block), whatever the rest of the board does. A star marks a cell every placement uses; a dot marks a cell no placement uses. The apps show the same sheet under Learn; every card is checked by enumerating the placements, so a drawing never says more than the placements do.

• A line of three

  Three cells in a row with two stars: the ends are the stars, since the middle touches both.

• The 2×2 block

  Any 2×2 block holds one star at most: two inside it would touch. A region that needs two stars must offer two 2×2 blocks apart.

• The 2×3 rectangle

  Two stars two columns apart at least: the middle column is out, one star in each end column.

• The 3×3 square

  The centre touches every other cell, so it is out; the two stars sit on the rim.

• The L of four

  The far end of the long arm is a star, and the cell next to it is out: the second star must be in the foot.

• The S of four

  Only the two ends are far enough apart: both are stars, the two middle cells are out.

• The T of five

  The top of the stem touches every other cell, so it is out. The bar’s centre stays possible: it is two rows above the stem’s foot.

• The plus

  The centre is out, and the two stars are the two ends of one arm: neighbouring arms touch at the corner.

• The P of five

  The tail is a star and the two cells above it are out: the other star is in the top row of the block.

• The U of five

  The bottom centre touches both arms and the two cells beside it, so it is out; the stars are spread between the arms.

• The W of five

  The middle step touches every other cell, so it is out; the stars are one on each side of it.

Where to practise

• Learn, on the app's Home screen: one lesson per idea on this page. Each explains the idea on a real position, has you make the deduction, shows a second board, then offers Practice this idea: fresh positions keyed on that idea, untimed, no lives, a counter of solved positions.
• Hints: on any ordinary board, Show me where highlights the unit behind the next step, then the cells, names the idea and offers Learn this, which opens its lesson and comes back to your game.
• Tactics: a three-minute rush of positions to read, each cut from a fresh board by the same engine; a miss shows the answer with the idea behind it.

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The boards on this page are the lesson boards of Stelline 1.6; the texts are the lessons’ and the hint ladder’s. Last updated 16 October 2026.