Star Battle Strategies: Regions, Counting and Squeezes
Every Star Battle technique in the order you need it, from marking around stars to counting regions in rows and 2x2 blocks, with a full 6x6 solve.
The best Star Battle strategy is a fixed order of techniques: mark around every star, solve the smallest regions first, rule out squares that every option touches, use regions that fit in one row or column, then count groups of regions against groups of rows. The 2x2 rule (no 2x2 block holds two stars) adds one more tool, and it is essential in two-star puzzles. This guide teaches each technique, most with a diagram, then solves a full 6x6 puzzle with them.
It is written for players who know the rules and have solved a few easy grids. If you have not, read how to play Star Battle first. The examples use the one-star rules, as in Puzzle Picnic's Stars: one star in every row, column and region, and no two stars touching, not even at a corner. A section near the end covers what changes with two or three stars. Squares are named by row and column from the top left, so R2C3 is row 2, column 3. In the diagrams, ? marks the open squares of whichever row, column or region the text is talking about, and x marks a square that cannot hold a star.
Technique 1: mark everything around every star
Every star rules out four groups of squares at once: its eight neighbours, the rest of its row, the rest of its column and the rest of its region. Marking all four groups the moment you place a star is the habit that prevents most stalls.
It sounds too basic to count as strategy, but nearly every later technique depends on knowing exactly which squares are still open. A corner neighbour you forgot to mark makes a region look as if it has three options when it really has two, and the deduction you needed never shows up.
KrazyDad's tutorial for its two-star puzzles calls the row, column and region part the Rule of Finished Containers: once a row, column or region has all its stars, the rest of it is empty. In a one-star puzzle every star finishes three containers at once. Make it a ritual:
- Place the star.
- Mark its eight neighbours.
- Mark the rest of its row and column.
- Mark the rest of its region.
- Only then look at what has changed.
Step 5 matters. Each batch of marks can leave a row, column or region with a single open square, and that is your next star. Scan the lines and regions that the new marks touched before you go looking elsewhere.
Technique 2: start with the smallest regions
Small regions are where Star Battle begins, because a region with few squares has few places for its star. A region of one square is a star outright. A region of two, three or four squares can only hold its star in a handful of places, and any square that all of those places would rule out can be marked straight away. The UK Puzzle Association's Star Battle guide makes the same point: start with small regions and thin ones.
The idea behind this is worth stating on its own: if a square touches every open square of a region, it cannot hold a star. Whichever square gets the region's star, that square would touch it. The same is true for a row or column with only a few open squares left. Each region shape therefore has a predictable footprint:
| Region's open squares | Squares it rules out outside itself |
|---|---|
| One square | It is the star: its eight neighbours, its row and its column |
| Two side by side | The rest of their row (or column), plus the two squares on each long side: four in all |
| Two on a diagonal | The other two corners of their 2x2 block |
| Three in a straight line | The rest of their row (or column), plus the square on each side of the middle one |
| An L of three | The fourth corner of their 2x2 block |
| A 2x2 block | Nothing on its own; pair it with counting (technique 4) |
Here is the two-square case, which you will meet in almost every puzzle.
And the L of three, which is easy to miss because it rules out just one square:
Notice that the table talks about open squares, not the region's full shape. A big region shrinks as you mark it, and a ten-square region with eight squares marked behaves exactly like a region of two. Recheck the shape of a region every time marks land in it.
Technique 3: regions that fit in one row or column
When every open square of a region lies in a single row, the region's star must be in that row. That row can only hold one star, so every square of the row outside the region is empty. The same goes for columns.
The mirror image is just as useful: when every open square of a row lies inside one region, the region's star must be in that row, so the rest of the region is empty. This often happens at the top or bottom edge, where a long region runs along a whole row. In the first puzzle of our how-to-play guide, row 1 belonged entirely to one region, which ruled out two squares further down at once.
Both versions are quick to scan for. For each region, ask: are its open squares all in one row, or all in one column? For each row and column, ask: are its open squares all in one region? A yes to any of these gives marks.
KrazyDad's tutorial calls the region version part of its Rule of Container Cabals, which is also the bridge to the next technique: the same reasoning works with two, three or more regions at once.
Technique 4: counting N regions in N rows
The counting technique is the one that solves harder Star Battles: if N regions lie entirely inside N rows, the stars of those N rows all belong to those N regions, so every square in those rows outside the N regions is empty. It works for columns too, and in reverse.
The reason is a count. N rows hold exactly N stars between them. N regions also hold exactly N stars, and if all of those regions' open squares lie inside the N rows, their N stars are all in those rows. That uses up every star the rows have. Any other square in the rows would be one star too many.
The reverse version: if all the open squares of N rows lie inside N regions, those N regions get their stars from these rows, so the rest of those regions is empty. Technique 3 is simply the case N = 1.
How to look for it:
- Start at the edges. Regions squeezed against the top, bottom or sides are the likeliest to fit inside a band of two or three rows or columns.
- Count small regions together. Two small regions sitting in the same two rows, or two thin regions sharing the same two columns, are the classic case.
- Count with open squares, not shapes. A region that sprawls over four rows may have its open squares in just two of them after a few marks.
Larger groups (three regions in three rows, four in four) are where puzzles get properly hard, because the pattern is spread across the grid. In Puzzle Picnic's Stars, Expert puzzles need reasoning about groups of regions together, and Hard puzzles sometimes do. Our post on squeezing regions has more worked examples of region groups.
Technique 5: 2x2 blocks never hold two stars
Any two squares in a 2x2 block touch each other, either along a side or at a corner, so a 2x2 block can hold at most one star. This simple fact has two main uses.
In one-star puzzles: a cramped region acts like one fat square. If all of a region's open squares fit inside a 2x2 block, the region's star is somewhere in that block, and anything touching every open square is ruled out. With three open squares in an L, that is the fourth corner (as in technique 2). With all four squares of the block open, nothing outside is touched by all four, but the region is now confined to two rows and two columns, which is exactly what technique 4 needs. Two such regions side by side in the same two rows rule out everything else in those rows.
In two-star puzzles: four-square counting. In a 10x10 grid with two stars per row, any two neighbouring rows hold four stars, and those two rows split neatly into five 2x2 blocks. Each block holds at most one star, so four of the five blocks hold exactly one, and only one block is empty. As soon as you rule out a whole block, each of the other four must hold exactly one star, and you can treat each of them like a small region. KrazyDad's tutorial builds its Rule of Four-Squares on the same idea, and it is the backbone of two-star solving.
The 2x2 rule also catches mistakes. If you find two stars inside one 2x2 block, they touch, and one of them is wrong. Puzzle Picnic shows this the moment it happens: two stars that break a rule turn red and count as a mistake.
A worked 6x6 puzzle, step by step
This one-star puzzle uses the first four techniques, including one counting step that nothing simpler can replace at that point. It is the size of Puzzle Picnic's Easy level, but it needs more than a typical first puzzle.
Step 1: region D fits in column 5 (technique 3). D's two squares are both in column 5, so the rest of column 5 is empty: R1C5, R2C5, R3C5 and R6C5.
Step 2: squares that touch both of D's squares (technique 2). R4C4, R4C6, R5C4 and R5C6 touch both R4C5 and R5C5, so they are empty.
Step 3: region E fits in column 1. The same idea: R1C1, R2C1, R3C1 and R4C1 are empty.
Step 4: squares that touch both of E's squares. R5C2 and R6C2 touch both R5C1 and R6C1, so they are empty.
Step 5: region C is now an L (technique 2). C's open squares are R3C2, R4C2 and R4C3: an L of three. R3C3, the fourth corner of their 2x2 block, touches all three, so it is empty.
Step 6: two regions in two rows (technique 4). Look at rows 5 and 6. Region E's open squares are R5C1 and R6C1. Region F's open squares are R5C3, R6C3, R6C4 and R6C6. Both regions lie entirely inside rows 5 and 6, so the two stars of those rows belong to E and F. The only other open square in rows 5 and 6 is R5C5, which belongs to D, so it is empty. That leaves region D with one square, R4C5: the first star.
At this point none of the earlier techniques gives anything new, so the counting step is the only way forward. Harder puzzles are built around moments like this.
Step 7: row 3 has one square left. The star in R4C5 ruled out R3C4 and R3C6, so row 3's only open square is R3C2. Place a star there (region C's) and mark around it, which rules out R2C2, R2C3, R1C2 and the rest of column 2.
Step 8: region A has one square left. A's only open square is now R1C3, so it is a star. Its marks rule out R1C4, R2C4 and R1C6, and the rest of column 3, including R5C3 and R6C3.
Step 9: the rest falls into place. Row 2's only open square is R2C6: a star. Row 5's only open square is R5C1: a star, for region E. Row 6's only open square is R6C4: a star, for region F.
Notice the order. The two-square regions did the first four steps, the L did one, and the single counting step broke the puzzle open. After that, every star was a row or region with one square left. Many puzzles follow this shape: a slow, careful opening and a fast finish.
Two-star and three-star puzzles: what changes
The same techniques work in two-star and three-star puzzles, with the numbers scaled up. Two stars per row, column and region is the classic form: the very first Star Battle, at the 2003 World Puzzle Championship, used two stars, and so does the New York Times' Two Not Touch. On puzzle sites such as KrazyDad, two-star puzzles are usually 10x10 and three-star puzzles 14x14. Our post on where Star Battle came from has that history.
What changes in practice:
| Idea | One star | Two stars |
|---|---|---|
| A finished row, column or region | After its one star | After its second star |
| A region with few open squares | Two side by side: the star is one of them | Two stars cannot be side by side, so a region of three in a row with two stars must use both ends |
| Counting N regions in N rows | N rows hold N stars | N rows hold 2N stars, so the same count works with doubled numbers |
| 2x2 blocks | At most one star | At most one star, and two rows split into 2x2 blocks give the four-square count |
The row about three-in-a-row regions is worth checking for yourself: in a two-star puzzle, a region of exactly three squares in a line needs two stars that do not touch, so they must be the two end squares. The middle square is empty, and so is everything touching either end.
Counting also gets subtler. With two stars, a region can split its stars across two bands of rows, so a common move is "this region puts at least one star in these rows". KrazyDad's tutorial calls a related idea the Rule of Container Consumption. Take your time with the numbers: write the count down if you need to.
A routine for when you are stuck
When a Star Battle stalls, run the techniques in order instead of staring at the grid. The order goes from fastest to slowest to check:
- Audit the marks. Pick each star and confirm its eight neighbours, row, column and region are marked. A missing mark is the cause of most stalls.
- Count every unit. For each row, column and region, count its open squares. A count of one is a star. A count of two or three is a candidate for technique 2.
- Check shapes. For each region with a few open squares, ask whether they fit in one row, one column or one 2x2 block.
- Check lines against regions. For each row and column, ask whether its open squares all sit in one region.
- Count in pairs. Take each pair of neighbouring rows and each pair of neighbouring columns, and ask which regions fit entirely inside them. Then try groups of three.
In Puzzle Picnic, a puzzle's difficulty depends on which solving techniques it needs, so expect to reach step 5 more often on Expert. If you still find nothing, a hint in Puzzle Picnic explains the next logical step rather than just placing a star, and reading the reason is a quick way to learn the technique you missed. For the slips that most often cause a stall, see Star Battle mistakes to avoid.
Frequently asked questions
What is the best first move in Star Battle?
Find the smallest region and work out what its few options have in common. A region of one or two squares almost always gives a star or a batch of marks straight away, and the marks from that first star usually shrink the next region.
Do you ever need to guess in Star Battle?
No, not in a well-made puzzle. A fair Star Battle has exactly one solution and a logical path to it. If you feel you have to guess, a mark is usually missing, or a counting step (technique 4) is waiting to be found.
What is the 2x2 rule in Star Battle?
Any 2x2 block of squares can hold at most one star, because every two squares in it touch. In two-star puzzles this lets you split two neighbouring rows into 2x2 blocks and count the stars in them. In one-star puzzles it lets you treat a region squeezed into a 2x2 block as one fat square.
Do the same strategies work for LinkedIn's Queens?
Yes. LinkedIn's Queens follows the one-star rules: one crown in every row, column and coloured region, with no two in touching squares. Every technique in this guide works there unchanged. Our post on Queens and Star Battle compares the two in more detail.
How do I get faster at Star Battle?
Speed comes from scanning in a fixed order, not from rushing. Use the stuck routine above on every puzzle until it becomes automatic, and mark in batches: place a star, mark all four groups, then check the units the new marks touched.
Where to go next
Take one technique at a time. For a week, solve small grids and say the reason for each mark aloud, especially "this region fits in one row" and "these squares touch every option". When those come without effort, start each puzzle by counting pairs of rows and pairs of columns, which is where the real step up lies.
Puzzle Picnic's Stars runs from a 6x6 Easy grid to a 9x9 Expert grid, and our guide to what changes at each level shows how the techniques line up with them. The Stars page has the rules and a Play button, and it plays in the browser.