Star Battle is a placement puzzle with three counting rules and one spacing rule. The square grid is cut into irregular outlined regions, as many regions as there are rows. Your job is to put exactly one star in each row, each column and each region, and no two stars may touch, not even at a corner. Every puzzle here is generated fresh and checked by a solver so that it has exactly one answer.
How to play
The rules.
- Each row contains exactly one star.
- Each column contains exactly one star.
- Each outlined region contains exactly one star.
- Stars never touch. None of the eight cells around a star can hold another star.
Marking cells. Tap a cell to cycle through three states: a dot (meaning “no star here”), a star, and empty again. You can also select a cell and use the ★ Star and · No star buttons, or Erase. On a keyboard, S or * places a star, the full stop places a dot, and Backspace clears; the arrow keys move between cells.
Dots are only notes for yourself. The puzzle counts as solved the moment every star is in the right place, whether or not the other cells are dotted.
Mistakes and help. If two stars break a rule (same row, column or region, or touching), both are highlighted. Hint fixes a wrong mark if you have one, otherwise it places one correct star. Undo takes back your last change. The timer and the number of hints you used appear when you finish.
Difficulty. Choose under Difficulty at the top; New puzzle creates another grid at that size.
| Level | Grid | Stars to place |
|---|---|---|
| Easy | 5 × 5 | 5 |
| Medium | 6 × 6 | 6 |
| Hard | 8 × 8 | 8 |
Solving techniques
Star Battle is solved almost entirely by ruling cells out. A typical solve is mostly dots, with stars appearing once the dots leave no choice.
Start with the smallest region. A region of two or three cells has very few possible star positions, and often all of them share a row or column. When every cell of a region lies in one row, that row’s star must be inside the region, so dot every other cell in that row.
Surround every star. Each time you place a star, dot its eight neighbours and every other cell in its row, column and region. This is mechanical, but it is where most of the next deductions come from.
Look for cells that see a whole region. If placing a star in some cell would dot out every cell of a neighbouring region, that cell can’t hold a star. Small regions next to each other often eliminate cells this way.
Count regions against rows. If two regions together fit entirely inside two rows, those two rows’ stars are both used up by those regions. Every other cell in those two rows can be dotted. The same idea works for three regions in three rows, and for columns. On the 8 × 8 grids this is often the key step.
Use the touching rule in 2 × 2 blocks. A 2 × 2 block can hold at most one star, because any two cells in it touch. When a row needs its star in one of two adjacent cells, the cells directly above and below both of them are ruled out.
Never guess. Each grid has a unique solution, so a logical next step always exists. If you are stuck, recheck the regions you have not counted yet; one of them is nearly always down to two cells.
Strategy for the larger grids
On the Hard 8 × 8 boards, work region by region rather than row by row. Write dots generously; on a larger grid it is easy to forget that a cell is already excluded. When a region gets down to two possible cells, check the cells that both options would rule out: any cell adjacent to both candidates, or in the same row or column as both, can be dotted straight away.
If you prefer numbers to stars, Binary Grid is another pure-logic grid with a handful of strict rules.
If you enjoy Star Battle, try Sudoku or Tower of Hanoi next.
