Most broken Star Battle grids come from one of six mistakes, and the biggest is placing a star before it’s certain. The others are oversights: stars touching at a corner, a region forgotten, squares left unmarked, a two-star region given room for only one, and a wall misread. Each one is below, with how to spot it.
If you’re new, the rules and how to solve pages explain the ideas these mistakes go wrong on.
1. Placing a star before it’s certain
When a region has two or three places left, it’s tempting to pick one and see. Usually nothing tells you straight away. We took every one of the game’s levels, put a star in the first square that should be empty (choosing one that broke no rule yet), and kept making honest moves until the game showed a red mark:
| Track | Red mark appeared | Moves before it (median) | Longest |
|---|---|---|---|
| Easy 6×6 | 50 of 50 | 6 | 18 |
| Medium 8×8 | 50 of 50 | 7 | 27 |
| Hard 8×8, 2 stars | 48 of 50 | 27 | 45 |
On the other two Hard levels, the red mark never appeared at all: the honest moves ran out first. Here’s one on Medium level 3, with a wrong star in the top-left corner:
Eleven honest moves later, region h has no room left for its star. Region h is nowhere near the wrong star.
How to avoid it: only place a star when a technique makes it certain. If a region could still go more than one way, work somewhere else.
2. Forgetting the corners
Stars can’t touch at all, and that includes corner to corner. It’s the easiest rule to forget when you’re scanning rows and columns.
How to avoid it: every time you place a star, cross out all eight squares around it, not just the four beside it.
3. Forgetting the regions
Two stars can sit in different rows and different columns and still break the rules, by sharing a region.
How to avoid it: after placing a star, cross out the rest of its region as well as its row and column (on one-star puzzles).
4. Not crossing squares out
Most of the work is ruling squares out: 75 to 88% of the squares settled on the game’s levels are crosses. Without them, you can’t see when a region has squeezed into one line, or when a line has one place left.
How to avoid it: mark a square as soon as it’s certain to be empty, just as you would a star.
5. Leaving room for only one star on a two-star grid
On two-star puzzles, every region needs room for two stars that don’t touch. Two open squares side by side aren’t enough, and neither are three in an L. It’s easy to cross out a square that the second star needed.
How to avoid it: before crossing out in a two-star region, check it still has room for two stars that don’t touch. That’s no room and every arrangement at work.
6. Misreading a wall
Regions can be long and twisty, and it’s easy to lose track of which side of a wall a square is on.
How to avoid it: trace a region’s wall all the way round before you count its squares. In the game, the walls are drawn thick and the lines inside a region thin.
How to recover from a mistake
- A red ring or a red region means a rule is broken, but the mistake may be elsewhere, sometimes a long way back. Undo to the last move you were sure of.
- Press Stuck? It rings a wrong square before anything else, so you know exactly where.
- Stuck with no red mark? Look at the smallest regions again, then at when you get stuck.