When two regions’ open squares all lie inside the same two rows (or columns), those regions take all of those rows’ stars, so everything else in the two rows is empty. The other way round works too: two rows inside two regions clear the rest of the regions.
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 two regions that fit inside two rows, or two columns (or two lines that fit inside two regions).
- Check the stars match: the group of lines and the group of regions need the same number.
- Cross out everything in the other group that’s outside the first.
In a real puzzle
On the 8×8, it’s first needed at step 3. Every square of rows 7 and 8 belongs to region g or region h. The two rows need four stars and the two regions hold exactly four, so the regions’ squares in row 6 are empty.
How often you’ll need it
On 6 of the 50 Easy levels, 17 Medium and 31 Hard: 0.2 times per Easy level on average, 0.4 on Medium and 0.9 on Hard. It’s 1 of the 44 moves on the 8×8 here.