Star Battle Puzzle

The number in the upper right corner of the puzzle tells you how many stars you need to fit into each row, column and region.

Click a square once to mark it with a dash. This means that no star is here. Click again to mark it with a star. Click a third time to remove all marks.

You can also hover your mouse over a square and type an x or a - to mark a dash and type an s or * to mark a star. You can hover over a square and type any other character to place a temporary mark into the square for your reference. Hover over a square and type the delete key to clear any marks.

The goal is to use logic to determine where the stars are in the supplied grid. Only two stars can appear in each row, column and region. Also, no two stars may touch, even diagonally.

By looking at which stars are already in the different rows, columns and regions you can deduce where other stars may go, or at least eliminate spots where you know that they cant go. By examining multiple rows or columns at the same time, you can figure out where all the stars should go.

Forced Star

Examine this shape made up of 5 squares. Because it must contain two stars and because no two stars can touch, even diagonally, we know that the star must be in the indicated place and we can mark off all 8 surrounding squares.

Internal Elimination

Examine this shape made up of 6 squares. If the star went in the middle square, then there would be no other legal place to put the second star. Therefore this middle spot cannot contain a star.

External Elimination

Examine this horseshoe shape. Every possible combinations of two stars that it could contain would be adjacent to the square in the other shape, so it cannot contain a star.

Row/Column Elimination

Look at this small 4 square shape. It must contain two stars, which means that the other squares in that row cannot. We can also use the "External Elimination" technique to mark off some additional squares.

Trial Star

Another common strategy is to find a spot where you know that a star must go into either one of two or three spaces. Then use pencil marks to place a trial star in a square and use additional pencil marks to indicate what this forces. If you get a contradiction or reach an impossible situation then you know that our initial guess was incorrect and it can be eliminated. If you don't reach a contradiction, it doesn't necessarily mean that your guess was correct. Back up and try the other candidates and see if they work as well. Sometimes you will have to make several guesses to find some additional clues.