When a region’s open squares all lie in one row (or column), that line’s stars are in the region, so the rest of the line is empty. And the other way round: when a row’s open squares all lie in one region, the region’s stars are in that row, so the rest of the region is empty.
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
- Look for a region whose open squares all fall in one row or one column, or a line whose open squares all fall in one region.
- Check the stars still needed match on both sides.
- Cross out everything else in the other one.
In a real puzzle
On the 8×8, it’s first needed at step 4. Row 6’s open squares all belong to region f. Row 6 needs two stars, so both of region f’s stars are in row 6, and region f’s squares in row 5 are empty.
How often you’ll need it
On 48 of the 50 Easy levels, 48 Medium and 36 Hard: 2.6 times per Easy level on average, 3.3 on Medium and 1.5 on Hard. It’s 3 of the 44 moves on the 8×8 here.