Star Battle
Star Battle puzzles, new every day. One star per row, column and region. Stars never touch. Rules, techniques and new puzzles every day in four levels.
Rules
- Place exactly one star in every row, every column and every coloured region.
- Stars never touch, not even diagonally.
- Crosses mark cells that certainly hold no star.
- Tap to switch between cross, star and empty.
- Drag to set several crosses at once.
- Right-click or long-press a star to cross out every cell it blocks.
- Keyboard: arrow keys move, space switches, X sets a cross, S a star.
Techniques
Every hint in the game names one of these techniques and shows where it applies.
Shadow
Every star blocks its row, its column, its region and the eight cells around it. Those cells get a cross straight away. Right-click or long-press the star to do it in one go.
Last spot
When a row, a column or a region has only one free cell left, the star goes there.
Shared shadow
Wherever the star of a unit ends up, some cells would be blocked by every option. Those cells are empty, even before you know where the star goes.
Subset
If the stars of k rows can only go in k regions, those regions belong to those rows. All other cells of the regions are empty. The same works for columns, and the other way round.
Either-or
When a unit has only two free cells left, try one of them. If it leads to a contradiction within at most two forced moves, the star belongs on the other. No puzzle asks you to think further ahead.