Star Battle 10x10
Place exactly 2 stars in every row, column, and outlined region. No two stars may touch, not even diagonally.
Mastering the 10x10 2-Star Format
The 10x10 grid with 2 stars is the international competitive standard of Star Battle, popularized by the World Puzzle Championship and the New York Times puzzle community. While 8x8 requires simple local deduction, 10x10 demands multi-line spatial counting and the Pigeonhole Principle.
1. The 2-Row / 2-Column Rule
Any 2 adjacent rows or columns must contain a combined total of exactly 4 stars. If 3 regions span entirely across those 2 rows, they must absorb all 4 stars, meaning all other squares in those rows are crosses!
2. 2x2 Cell Traps
Because no two stars may touch diagonally, any 2x2 square of 4 cells can contain at most ONE star. Use this constraint to eliminate crowded candidate squares.