Star Battle

Star Battle is a logic puzzle played on a grid divided into outlined, irregularly shaped regions. Solvers must place a specific number of stars (usually 1 or 2) into the grid so that every row, column, and outlined region contains exactly that required amount. The primary rule constraint is that stars cannot touch each other, not even diagonally.

The number of stars required depends entirely on the specific puzzle's rules, but most standard puzzles require placing either 1 or 2 stars per row, column, and region. The required amount is always stated at the top of the grid. Two-star puzzles are significantly more difficult to deduce than one-star puzzles.

The best strategy involves identifying rows, columns, or regions that overlap heavily with others, thereby eliminating potential star placements in neighboring areas. Players must meticulously mark off diagonally adjacent cells whenever a star is placed. Finding forced placements in small regions quickly cascades through the rest of the grid.

The puzzle was originally created by the Japanese puzzle company Nikoli. It was later popularized internationally under the name Star Battle. The puzzle's elegant simplicity combined with deep logical deductions has made it a staple in competitive puzzle competitions like the World Puzzle Championship.