To solve Star Battle, cross squares out. Every star clears the eight squares around it and the rest of its row, column and region. Small regions do most of the work early: a region squeezed into one row or column decides that line’s stars, and a square whose star would leave a region no room is empty. Most moves cross squares out; stars appear when a row, column or region is down to its last places. Seven techniques cover every puzzle in the game.
New to Star Battle? Read the Star Battle rules first. This page assumes you know the two rules: the same number of stars in every row, column and region, and no two stars touching.
1. Neighbours
Stars never touch, so every square around a star is empty: all eight of them, corners included. Cross them out as soon as you place a star.
2. Finished rows, columns and regions
A row, column or region with all its stars is empty everywhere else. One with exactly as many open squares left as stars still needed: those squares are all stars.
3. Confined regions
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. It works the other way round too: when a row’s open squares all lie in one region, the rest of the region is empty.
4. No room
A square whose star would leave some row, column or region with no room for its stars is empty. Look for squares that touch every open square of a small region, or that would cross out the last places in a line.
5. Squeezed regions
The confined idea, with more than one region at a time. When two regions’ open squares all lie inside the same two rows (or columns), those regions take all of those rows’ stars, so every other square in the two rows is empty. It works with three, too, and the other way round.
6. Every arrangement
When a row, column or region has only a few places left, list every way its stars can fit, without touching. A square that every way crosses out is empty; a square that’s a star in every way is a star. It’s the workhorse of two-star puzzles.
7. What if
When nothing else works, pick a square and suppose it holds a star. Follow what that forces with the techniques above. If a rule breaks, the square is empty. The what-if page follows one through a real puzzle.
How often each technique is needed
We solved every one of the game’s 150 levels by following the hints, which always use the simplest technique that works. This is how many times each technique was used, on average, per level:
| Technique | Easy 6×6, 1 star | Medium 8×8, 1 star | Hard 8×8, 2 stars |
|---|---|---|---|
| Neighbours | 4.0 | 5.3 | 10.9 |
| Finished lines and regions | 10.3 | 15.9 | 12.4 |
| Confined regions | 2.6 | 3.3 | 1.5 |
| No room | 4.2 | 5.3 | 14.3 |
| Squeezed regions | 0.2 | 0.4 | 0.9 |
| Every arrangement | 0 | 0 | 6.0 |
| What if | 0 | 0 | 1.0 |
On the one-star tracks, finished lines and regions do the most work. Two stars change things: no room becomes the busiest technique, every arrangement is needed on every Hard level, and what-if on 17 of the 50.
An 8×8, solved in three stages
This is Medium level 25 from the game: one star in each row, column and region.
Stage 1: no room for the small regions
Regions c and d are small: five squares and three. A star in any of four squares nearby would touch, or share a row, column or region with, every open square of one of them, leaving it no room. All four are empty.
Stage 2: rows 7 and 8 inside regions g and h
Every square of rows 7 and 8 belongs to region g or region h. The two rows need two stars and the two regions hold exactly two, so the regions take the rows’ stars, and their squares outside rows 7 and 8 are empty. That empties row 6 apart from one square, which gets its star.
Stage 3: the rest
From there it’s crossing out and counting: 16 steps from finished rows, columns and regions, 5 rounds of neighbours and 2 confined regions finish the grid.
When you get stuck
- Cross out around every star, and the rest of its row, column and region once they’re full.
- Look at the smallest regions. Where can their stars go? What would each choice cross out?
- Look for lines and regions that fit inside each other, one at a time or in pairs.
- On two-star puzzles, list the ways a nearly full line or region can hold its stars.
- Don’t guess. Every puzzle here can be finished by logic.