Star Battle techniques

Star Battle is a puzzle of crossing things out. You rarely find a star directly; you rule out squares until only one place is left. These are the moves that do most of the work, shown on one-star boards like the daily puzzle and LinkedIn’s Queens.

In each picture, the cells the technique decides are outlined in blue.

1. Cross out around every star

   A star claims its whole row, column and region, and no other star may touch it, even at a corner. The moment you place one, cross out all of those squares.

2. A region inside one row

   If every open square of a region sits in one row, that region’s star is in that row. The row’s star is used up, so cross out the rest of the row. The same works for columns.

3. Two regions squeezed into two rows

   Here the two regions in the top middle and top right both fit inside the top two rows. Those two rows hold exactly two stars, and both must belong to those regions, so every other square in those rows is empty. It works for any number: three regions inside three rows, or three rows inside three regions.

4. A star that would wipe out a region

   Before placing a star, look at what it would cross out. A star in either marked square would touch both squares of the small region at the top, leaving it nowhere to go. A star anywhere else in the top row would take that row from it. So all of those squares are empty.

In two-star puzzles the same ideas apply with bigger numbers: a region inside two rows takes both of those rows’ stars. One extra fact helps there: a 2×2 block can never hold more than one star, which caps how many stars a small region or a pair of rows can take. When you’re stuck, pick a square, imagine a star in it, and follow the crossings until something breaks.