In the puzzle “Star Battle”...

In the puzzle “Star Battle”, you need to place stars so that each row, column, and outlined region contains exactly one star (or two stars in the more complex version). The stars cannot touch each other, not even diagonally.

Typically, the solving strategy is based on marking crosses in all cells where a star cannot be placed according to the puzzle’s rules. Then, for regions where there’s only one possible spot left for a star, we place it — and repeat the process until the puzzle is fully solved.

Let’s look at the solving algorithm using this example:
https://en.grandgames.net/starbattle/id576319

We have two regions shaped as vertical lines in the far left and far right columns. Since there must be a star somewhere within each of them, and only one star is allowed per column, we can exclude all other cells in those same columns.

In the neighboring columns, we can also exclude a few more cells, because they cannot contain a star — any star placed in the adjacent regions would touch them diagonally.

In the upper region, there is only one free cell left — we place a star there. In the lower region, a line is formed, allowing us to exclude the bottom-left cell and the middle one (because of the diagonal rule — no matter where the star is placed in that region, those cells would be diagonally adjacent).

Place a star in the remaining cell and mark a cross.

Once again, a region appears with only one possible cell for a star; after placing it, another such region forms below.

Finishing the solution:

The puzzle is quite simple and entertaining! Try it yourself:
https://en.grandgames.net/starbattle/id576319

A Star Battle with two stars per region is solved in a similar way. If you’ve mastered the technique, other players will appreciate a new article analyzing a large puzzle of this type.

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