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Star Battle Puzzle

In Diem this puzzle is called Garden: the stars are flowers, the regions are beds.

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One flower (star) per row, column and bed. They never touch, not even corner to corner.

 

Use the arrow keys to move between squares. Press F to plant a flower, X to dot a square, or Space to switch; Backspace clears.

Star Battle rules

A solved 5 by 5 Star Battle: one flower in every row, column and bed, and no two flowers touch.
  1. Every row and every column holds exactly one star.
  2. Every outlined region holds exactly one star.
  3. Stars never touch, not even diagonally.

That is the whole game. There is no arithmetic and no guessing: each board has exactly one solution, and you can reach it by asking, square by square, “can a star go here?” Most of the work is ruling squares out. Mark those with a dot (one tap) and plant a star (two taps) only when you are sure.

How to solve Star Battle

These are the ideas Diem's Hint button uses, from the first one you will need to the ones that crack the hard boards. The Hint names the idea and rings the square it proves, so you can learn them as you play.

1. Last Spot

The top-left bed is a single square, so its star must go there.
A region or line with one open square left must take its star there. The quickest case is a region of one square, like the top-left corner here. Later in a puzzle, the same thing happens once dots fill the rest of a region.

2. Cross Out

A star in the top row: its row, its column, its bed and the squares around it all get dots.
Every star clears its row, its column, its region and the eight squares around it. Dot them all straight away. Those dots are what turn other regions into a Last Spot.

3. Only Fit

The ringed square touches both squares of the small bed below it, so it can't hold a star.
A square that touches every open square of a region can't hold a star. A star there would touch, and so rule out, the whole region, leaving it empty. Small regions of two or three squares are where to look.

4. Lock

A two-square bed lies inside one row, so the other squares of that row get dots.
When a region lies inside one row, that row's star belongs to the region. Dot the rest of the row. It works the other way too: a row whose open squares all sit in one region gives that region its star, so the region's squares outside the row are empty.

5. Pairs

Two beds fit inside the top two rows, so the other squares of those rows get dots.
Two regions inside the same two rows take both of those rows' stars. Everything else in the two rows is empty. The same goes for three regions in three rows, and for columns. Reach for it when a Hard board stalls.

When even that runs out, try a careful “what if”: imagine a star on one square and follow its dots. If some region or line is left with no room, that square is empty. Diem's hints call this No Room.

One star or two?

Star Battle comes from puzzle championships, where the usual grid is 10 × 10 with two stars in every row, column and region. That version is longer and asks you to keep track of pairs of stars. What you play here is the one-star version on small grids: 5 × 5 on Easy, 6 × 6 on Medium and Hard. A board takes a minute or a few rather than half an hour, but the logic is the same, and every idea above works on the bigger puzzles too. If you finish Hard boards in a couple of minutes, the classic two-star puzzles are a good next step.

FAQ

How do you play Star Battle?

Place stars on the grid so that every row, every column and every outlined region holds exactly one star, and no two stars touch, not even at a corner. Here the stars are flowers: tap a square once to mark it empty with a dot, twice to plant a flower.

Does every Star Battle puzzle have only one solution?

Every board on this page does. Each one is made by a generator that counts the solutions and keeps the board only when there is exactly one, and that can solve it step by step without a guess.

What is the difference between 1-star and 2-star Star Battle?

Classic Star Battle puzzles in books and contests usually ask for two stars in every row, column and region on a 10 × 10 grid. This page plays the one-star version on 5 × 5 and 6 × 6 grids. The rules are otherwise the same, and the solving ideas carry over.

What should I do when I am stuck?

Look for a region or line with only one open square left, then mark the squares around every star. If nothing shows up, press Hint: it rings a square you can work out and names the idea that proves it, without giving the answer away.

Can I play Star Battle on my phone?

Yes. The puzzle works with touch, a mouse or a keyboard (arrow keys to move, F for a star, X for a dot). Your best time for each difficulty is kept in your browser; there is no account to create.

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