Play Star Battle Online
Place exactly one star in each row, column, and colored region — no two stars may touch, not even diagonally. Pure logic, zero guesswork.
Created by Brian Hamilton
How to play Star Battle
Place stars on the grid so that every row, every column and every coloured region holds exactly the same number of them.
- Pick 1, 2 or 3 stars with the buttons above. That number applies to every row, every column and every region.
- No two stars may touch — not side by side, and not diagonally.
- Regions are the coloured shapes; they do not follow rows or columns.
- Every puzzle has exactly one solution.
Controls: tap a cell to place a star, tap again for a cross to mark it excluded, and once more to clear it. Marking crosses is how most of the board gets solved.
Tap to mark X, tap again for star
Two stars changes the puzzle, not just the count
Star Battle asks for the same three things at every level: a fixed number of stars in every row, in every column, and in every region, with no two stars touching — not even diagonally. Set that number to one and you have the puzzle LinkedIn made famous as Queens. Set it to two and you have the format used in the World Puzzle Championship, and a genuinely different solve.
The difference is that one star per row is a placement problem — each row has a single answer to find. Two stars per row is a packing problem. The two stars in a row cannot be adjacent, so they need a gap between them, and on an 8×8 board that single requirement removes most of the arrangements before you have looked at a region at all.
The technique that only exists at two stars
Here is the opening move that separates a competition solver from a beginner, and it has no 1-star equivalent.
If a region lies entirely within two rows, those two rows must hold all four of their stars inside it and one other such region. Two rows need four stars between them. A region trapped in those rows can only contribute stars to them. Count the regions confined there, and if they account for all four, every other cell in those two rows is empty.
This is not a rare shape. On these boards, an average of 2.1 regions on an 8×8 sit entirely within two rows, and about 1.9 within two columns on a 9×9. Most boards give you at least one, and it is nearly always the cheapest place to start.
The same logic runs the other way. A region spanning many rows is weak — it constrains almost nothing. Look for the squashed regions first and leave the sprawling ones until the board has closed in around them.
Region size tells you how hard a region is
Every region holds exactly two stars regardless of its size, so a small region is a tight constraint and a large one is loose. Regions average 8 cells on an 8×8 board and 9 on a 9×9 — one region per row, on average, the same as the grid dimension.
The smallest regions are where the board cracks. A region cannot be smaller than three cells — two stars need two cells that do not touch, plus a gap — and three-cell regions do turn up. When one does, it is solved on sight: there is exactly one way to place two non-touching stars in three cells.
That floor is itself a difference from the 1-star game, where a region of one or two cells is perfectly ordinary. Every region here has to be big enough and shaped well enough to hold two stars apart, which is why the regions look chunkier than the ones on the Queens board.
| Board | Regions | Mean size | Smallest | Confined regions |
|---|---|---|---|---|
| 8×8, 2 stars | 8 | 8.0 | 6 | 2.1 |
| 9×9, 2 stars | 9 | 9.0 | 5 | 1.9 |
| 10×10, 2 stars | 10 | 10.0 | 3 | 1.8 |
| 12×12, 3 stars | 12 | 12.0 | 8 | 3.1 |
“Confined regions” counts those sitting entirely within as many rows as there are stars — the shape the opening technique above depends on. There is roughly one on every board at two stars, and three at three stars.
Where solvers get stuck
Forgetting diagonals. Stars may not touch at corners either. This catches people constantly at two stars, because the extra star per row means far more near-misses. Any star you place rules out up to eight neighbours.
Counting rows but not columns. The row, column and region constraints are separate and all binding. A board that satisfies every region and every row can still be wrong on a column, and columns are the ones most people forget to audit.
Working cell by cell. At two stars the productive unit is the row-pair or the region, not the cell. Ask "where can this region's two stars go?" and enumerate, rather than asking "can a star go here?" of every square in turn.
Marking only stars. Marking cells you have excluded matters more at two stars than one, because the eliminations are what reveal the forced placements. The board fills with crosses long before it fills with stars.
What you can check about these puzzles
Every puzzle has exactly one solution, and unlike most puzzles on this site that was already true before this page was rewritten. The generator places the stars first, grows regions around them, and then counts the solutions, discarding any board that has more than one. 56 boards across 1-star, 2-star and 3-star at every offered size were re-checked against a separate counter written from the rules alone; all 56 were unique, and none broke a rule.
Three star counts, and they are three different games. One star is the Queens puzzle. Two stars is the competition standard. Three stars, on the larger boards, pushes the packing constraint further still — three non-touching stars in a row need at least five columns, so a 12×12 grid is barely wide enough. The confinement technique gets stronger to match: a 12×12 three-star board carries about three regions inside any three rows, against roughly two at two stars.
Star Battle and Queens
Star Battle is the older name and the broader puzzle; it appears in Nikoli collections and is a fixture of championship sets. Queens is the one-star version under a different name, popularised as a daily puzzle in 2023.
They share a grid and a rule set, so if you have played one the other will feel immediately familiar. What changes with the second star is which techniques pay: at one star you are eliminating candidates, and at two you are counting capacity — how many stars a group of rows or regions can hold between them.
More puzzles like this
If you like placing pieces under constraints, try these: