A row, column or region that has all its stars is empty everywhere else. One with exactly as many open squares left as stars still needed: those squares are all stars.
This is one of the Star Battle techniques. Each page shows its technique on the same two-star 8×8 from the game, Hard level 34.
The rule
- For each row, column and region, count its stars and its open squares.
- If it has all its stars, cross out every open square in it.
- If its open squares exactly match the stars it still needs, they’re all stars.
In a real puzzle
On the 8×8, the second kind is first needed at step 19. Row 8 needs two stars and has exactly two open squares left, columns 5 and 7. Both are stars.
How often you’ll need it
On every one of the game’s 150 levels, and more than any other technique on the one-star tracks: 10.3 times per Easy level on average, 15.9 on Medium and 12.4 on Hard. It’s 14 of the 44 moves on the 8×8 here.