Star Battle techniques: how to solve every board

Technique 1 · basic

The last free tile

Every row, every column and every color needs exactly one star, so each of them asks the same question: where does its star go? When all the tiles of one of them but one are ruled out, the answer is the tile that is left. It sounds too simple to count as a technique, but it is the step that turns your dots into stars. Most of the work in Star Battle is ruling tiles out, and this is where that work pays off. Check the colors first, because they are the easiest to lose track of: a row is quick to scan, a winding color of seven tiles is not.

Make it a habit after every batch of dots: look at each row, column and color that just lost a tile and count what is left. If one of them has no free tile at all, an earlier dot was wrong. Find it before you go on.

Where to look: small colors, and any row or column that just got a new dot.

Technique 2 · basic

Clear around every star

A new star settles four things at once. Its row, its column and its color now have their star, so every other tile in them is empty. And no star may touch it, so the eight tiles around it are empty too. Put those dots down straight away. A star with blank tiles around it is the most common reason a solve stalls, because every later technique reads only the tiles that are actually ruled out. On a 6x6 board, one star near the middle clears more than a third of the grid.

The corner tiles matter most, since they are the only ones the row and column don't already cover. They often decide the next step: a dot at a star's corner can take away the last spare tile of the color next door, and that color's star is then forced.

Where to look: the four corner tiles of each new star, and the colors that touch them.

Technique 3 · basic

A color inside one row

If every free tile of a color lies in one row, that color's star is somewhere in that row. The row's one star is then spoken for, so every tile of the row outside the color is empty. Columns work the same way. Solvers call this confinement, and it is the first technique that works on an empty board: before you place anything, look for colors that are flat strips of two or three tiles. Each of them clears the rest of its row or column for free.

Later in the puzzle the color doesn't have to be drawn as a strip. A large color that dots have cut down to a few tiles in one line is confined just the same, and those are the ones people miss. Check a color again whenever it loses tiles.

Where to look: colors that are short, straight strips, and colors that earlier dots have cut down to one line.

Technique 4 · intermediate

A row inside one color

This is confinement turned around. If every free tile of a row belongs to one color, the row's star is that color's star. The color is then finished, so all its tiles outside the row are empty. It works for columns too. The pattern shows up once a few stars have cleared most of a row: the tiles left over are often neighbors, and neighbors tend to share a color. It hits hardest with big colors that spread over several rows, because they lose many tiles at once.

Most players check colors against rows but forget to check rows against colors, so this one is easy to overlook. After each round of dots, read the free tiles of every row and column and ask whether they are all the same color.

Where to look: rows and columns with two or three free tiles left, side by side.

Technique 5 · intermediate

Tiles that touch a whole small color

A color of two, three or four tiles has its star on one of them, whichever it turns out to be. Any tile outside the color that touches every one of those tiles, even only corner to corner, can never hold a star: a star there would rule out the whole color. For two tiles side by side in a row, that is the two tiles above the pair and the two below it. For an L of three tiles, it is the tile in the corner the L wraps around. It is clearing around a star, applied to a star you haven't found yet.

The tiles don't have to be a whole color from the start. A big color that dots have cut down to two or three free tiles works the same way, and so do the last free tiles of a row or column, which is the next technique.

Where to look: colors of two to four tiles, especially pairs and L shapes.

Technique 6 · intermediate

Would it block a row?

Take a row with only two or three free tiles left, close together. A star in the row above or below that touches all of them would leave the row with no place for its own star, so the tiles that touch them all are empty. This is the previous technique applied to a row instead of a color, and many medium puzzles hinge on it. Columns work the same way, looking left and right. Two free tiles side by side give up to four such tiles, two above and two below. Three in a row give only two: the tiles directly above and below the middle one.

The test works on any tile: imagine a star on it, picture everything that star would clear, and see whether some row, column or color is left with no free tile. If one is, the tile gets a dot. Try it on tiles next to short rows and tiny colors; testing tiles at random is slow.

Where to look: rows and columns down to two or three free tiles side by side.

Technique 7 · advanced

Two colors in two rows

Counting works across several rows at once. If two colors both lie entirely inside the same two rows, each of them puts its star in those rows. Two rows hold only two stars, so both are taken, and every tile in those rows that belongs to another color is empty. Two colors inside two columns work the same way. Spotting it takes a different way of looking: instead of one color at a time, take a band of two rows and ask which colors fit completely inside it.

It runs the other way too. If two rows have all their free tiles inside the same two colors, those colors spend their stars in the two rows and are empty everywhere else. Pairs of small colors often sit along the edges and in the corners, so start there.

Where to look: bands of two rows or two columns along the edges, with two small colors in them.

Technique 8 · advanced

Three colors in three rows

The same count scales up. Three colors whose free tiles all lie inside three rows take all three stars of those rows, so every other tile in those rows is empty. This is often called the pigeonhole rule: three stars, three colors, no room for a fourth. It is the hardest Star Battle technique to see, because the three colors rarely look related. One can be a long strip, another a block in the corner, the third a big color that dots have trimmed. On 7x7 and 8x8 boards it is often the only way forward.

Count the free tiles, not the shapes: a color that once reached row 4 still counts if all its tiles there are ruled out. To search, take each band of three neighboring rows or columns and list the colors that sit fully inside it. Three colors give you the step. Four mean an earlier mark is wrong.

Where to look: the top three and bottom three rows, then the outer columns, once a few dots have trimmed the colors.

Common mistakes

• Skipping the corner dots. A star rules out the four tiles at its corners too. Leave them blank and confinement and counting stop working, because both depend on knowing which tiles are still free.
• Judging a color by its outline. A color that looks far too big for one row may have only two free tiles left, both in that row. Read the dots, not the borders.
• Checking colors against rows, but never rows against colors. Techniques 3 and 4 are a pair. Run both after every new star.
• Guessing when stuck. Every Starlit board can be finished without a guess. When nothing seems to work, go through the techniques in order on every row, column and color. The step you missed is usually a would-block or a two-color count.