How to solve Star Battle
Two stars in every row, column and region, and no two stars touching. Fence regions into their rows, test the squares beside them, and place stars where only two spots are left.
How it works
A Star Battle board is split into outlined regions. Place two stars in every row, every column and every region. Stars can’t touch, not even at a corner.
Three moves solve most boards. One: when a region fits inside one row, its two stars are that row’s two stars, so the rest of the row is empty. Two: test a square by supposing a star there. If a row, column or region would lose the room it needs for its stars, the square is empty. Three: when a line or region has exactly two open squares left that don’t touch, both are stars.
You never need to guess. Every Star Battle here has a unique solution that these moves reach.
Where to look first
Small regions and regions along an edge have the fewest ways to hold two stars. Look for one that fits inside one or two rows or columns.
A region of three squares in a line has only one way: the two ends. A region shaped like a 2×2 block can’t hold two stars at all, so boards never have one.
After every star, dot its eight neighbors. Then look at the rows, columns and regions it just squeezed.
Worth memorizing
Two stars per row, column and region.
An 8×8 board holds sixteen.
A region inside one row owns that row’s stars.
Dot the rest of the row.
Test a square: would a star there leave some line without room?
Then it is empty.
Practice
0 of 3 rightOn the empty board, which region lies entirely inside one row?
Row 1 still needs its two stars. How many ways can they fit in its open squares?
Row 7 needs two stars. Where do they go?