Star Battle Puzzles
Place stars so that every row, every column and every bold-bordered region holds exactly one — and no two stars touch, not even at a corner. Tap once for a star, again to cross a cell out. Every grid has exactly one answer, reachable without a single guess.
Also played in newspapers as Two Not Touch, and in the harder two-star form on larger boards.
What Is A Star Battle Puzzle?
Star battle gives you an empty grid divided into bold-bordered regions and asks for nothing but stars. Each row, each column and each region must end up with exactly one, and no two stars may touch — horizontally, vertically or diagonally. There are no numbers, no sums and no clues beyond the region borders themselves, which makes it one of the purest placement puzzles there is. It reaches most newspaper readers under the name Two Not Touch, printed daily in its two-star form.
Elimination Is The Whole Game
A placed star answers one cell. Its consequences answer up to twenty: the rest of its row, the rest of its column, the rest of its region, and all eight neighbouring cells are ruled out in one stroke. Nearly every deduction in star battle is an elimination — the stars themselves usually arrive as the last cell standing in some row, column or region rather than as a direct find. That is why crossing out is a first-class move on this board rather than an afterthought.
The pin, in both directions. If every cell a region has left sits in one row, that row's star must be that region's star — so the row's other cells are out. And if every cell a row has left sits in one region, that region is spoken for — so its cells in other rows are out. These two mirror-image deductions carry almost every hard star battle, and the hint button will name them when they apply.
How The Openings Work
- Find the smallest region. A region squeezed into one or two cells decides quickly, and its consequences spread furthest.
- Cross out everything a star touches. Row, column, region, and all eight neighbours. Do it immediately, every time.
- Watch for claimed lines. A region confined to one row claims it; a row confined to one region gives itself away. Both directions matter.
- Count down to one. Any group with a single live cell left places its star. Most stars land this way.
Why These Grids Stop At 7×7 — A Measured Limit
The one-star form gets rarer as the board grows, and at 8×8 it effectively stops existing: more than a thousand generated candidates produced zero grids with a single answer. That is the same wall kakuro hit past 24 cells — too few constraints per cell to pin one solution. The classic remedy at larger sizes is the two-star form, where every row, column and region holds two stars; that variant is a genuinely different build and is not offered here yet. The sizes that are offered are honest: every 5×5, 6×6 and 7×7 grid served has exactly one answer, checked rather than hoped.
| Grid | Stars | Cells | Single-answer grids | Offered here |
|---|---|---|---|---|
| 5×5 | 5 | 25 | Common | Yes — 20 grids |
| 6×6 | 6 | 36 | Common | Yes — 20 grids |
| 7×7 | 7 | 49 | Uncommon | Yes — 20 grids |
| 8×8 | 8 | 64 | None found | No — needs the two-star form |
The pattern is the one every constraint puzzle runs into: a cell is held down by its region and by its row and column, and as the board grows those hold proportionally less of it. Doubling the stars is what restores the grip, which is why every published 10×10 star battle you will find is a two-star puzzle.
The Two Families, And What Changes Between Them
Half the grids here hold their stars tight — neighbouring rows may put their stars just two columns apart, the closest the touching rule allows — and half hold them spread wide, at least three columns apart. Spread stars stretch the regions that contain them, so the wide families play as longer chains of pins; tight families lean harder on the crossing-out around each star. A five-by-five cannot spread its stars three apart at all — there is no legal arrangement — which is why the smallest size comes in one family only.
Star Battle Puzzles Frequently Asked Questions
What is a star battle puzzle?
A logic puzzle on a grid divided into bold-bordered regions. Place stars so every row, column and region holds exactly one — and no two stars ever touch, not even diagonally. It also appears in newspapers as Two Not Touch.
What are the rules of star battle?
Three. Every row, column and region holds exactly one star. No two stars touch, even at a corner. And that is all — no arithmetic, nothing to count beyond the stars.
What is the first move in a star battle puzzle?
Find a small region squeezed into one row or column — wherever its star lands, that line is used up, so every cell of the line outside the region is out at once. The smallest region is nearly always the way in.
Why do crosses matter more than stars?
A star answers one cell; its consequences rule out up to twenty — the row, the column, the region and all eight neighbours. Nearly every deduction is an elimination, and marking them is what makes the next star findable.
Can two stars touch diagonally?
No — and this is the rule that separates star battle from most placement puzzles. No shared edge or corner, which means stars in neighbouring rows always sit at least two columns apart.
Why do the puzzles here stop at 7×7?
Because the one-star form measurably stops producing single-answer grids at 8×8 — over a thousand generated candidates produced none. Larger boards are played in the two-star form, which is not built here yet.
Does every puzzle here have one answer?
Yes, and it is checked two ways: an exhaustive count over every legal star arrangement confirms exactly one fits, and a separate solver restricted to human reasoning must finish without guessing.