How to play Star Battle
Star Battle has three rules and no arithmetic. Everything else is working out where the stars cannot go.
- One star in every row and column. Each row needs exactly one star, and so does each column. No more, and no fewer.
- One star in every region. The heavy outlines divide the grid into regions, one per row. Each region needs exactly one star too — so every star has to satisfy all three at once.
- Stars never touch. No two stars may sit next to each other, including diagonally. A star placed anywhere rules out all eight cells around it.
Placing stars and crosses
Tapping a cell rules it out; tapping again takes the cross off. A star takes a double tap, a long press, or the S key. Most of solving is ruling cells out, which is why that is the cheapest gesture. Drag across a row to rule out several at once.
What that looks like on a real board
Here is one of the gentlest 7×7 boards on the site, before anything has been placed. The heavy outlines are the regions; there are 7 of them, and 7 stars to find.
These are the first 4 ideas the solver needed, in the order it needed them. Each one is a thing you can see rather than a thing you have to try.
Step 1: the highlighted region and row
Every open cell of this region (region 1) is in one row, so that row (row 1) must take its star from this region.
On any board. When every open cell of a region sits in the same row, or in the same column, or spans just two of them.
Step 2: the highlighted region
This region (region 2) has two open cells left, and its star must be in one of them. Any cell touching both is out.
On any board. When a row, column, or region is down to two or three open cells sitting close together.
Step 3: the highlighted row and region
Every open cell of this row (row 7) is in one region, so its star must come from that region (region 7).
On any board. When every open cell of a row or column belongs to one region, or to just two.
Step 4: the highlighted column
This column (column G) has one open cell left.
On any board. Whenever eliminations have narrowed a row, column, or region down to just enough cells.
The rest of the grid comes the same way, one forced cell at a time, and the techniques page shows every pattern the game uses with a worked example of its own.
Two stars, and the sizes
Everything above holds with two stars instead of one: every row, column and region needs a pair, and no two stars may touch. That makes it a harder puzzle rather than only a bigger one, because a region can hold a star and still be owed another. Two of the sizes have a page of their own, 8×8 puzzles and 10×10 puzzles, with how many boards there are at that size, how hard they run, and which techniques they lean on.
You will never have to guess
Every puzzle here is checked before it is published: exactly one solution, reachable by logic alone. If you are stuck there is always a next step you can reason your way to, and the solving techniques page lists every one the game itself uses.
A new puzzle every day
The daily puzzle changes at midnight UTC, the same moment for everyone, so the puzzle you solved is the puzzle your friends solved. It follows a curve across the week: Monday is the easiest board of the week and Saturday the hardest.