Hard Star Battle answer — August 13, 2025

Full written solution

Every deduction from the walkthrough above, in order. Each technique is explained in the Star Battle strategy guide.

1. Starting position — the grid is split into regions (bold outlines). Each row, column, and region needs exactly two stars, and no two stars may touch.
2. 3-cell region rule: Middle cell can't hold a star (row 2, column 6).
3. Region completion: 2 stars needed, 2 candidates (row 1, column 6).
4. Mark 4 cells adjacent to stars as X (row 1, column 5).
5. Region completion: 1 star needed, 1 candidate (row 3, column 6).
6. Mark 5 cells adjacent to stars as X (row 3, column 5).
7. Region completion: 2 stars needed, 2 candidates (row 3, column 4).
8. Mark 5 cells adjacent to stars as X (row 2, column 3).
9. Region completion: 1 star needed, 1 candidate (row 5, column 5).
10. Mark 5 cells adjacent to stars as X (row 5, column 4).
11. Row 3 complete: Mark 4 remaining cells as X (row 3, column 1).
12. Column 6 complete: Mark 3 remaining cells as X (row 7, column 6).
13. Three candidates with two adjacent: Isolated candidate must hold a star (row 8, column 7).
14. Mark 5 cells adjacent to stars as X (row 7, column 7).
15. Region completion: 1 star needed, 1 candidate (row 6, column 7).
16. Mark 3 cells adjacent to stars as X (row 5, column 7).
17. Blocking rule: a star here would touch every other open cell in its region, leaving no room for the region's second star (row 1, column 3).
18. Three candidates with two adjacent: Isolated candidate must hold a star (row 1, column 4).
19. Row 1 complete: Mark 4 remaining cells as X (row 1, column 1).
20. Region completion: 1 star needed, 1 candidate (row 2, column 2).
21. Mark 1 cell adjacent to stars as X (row 2, column 1).
22. Region completion: 2 stars needed, 2 candidates (row 2, column 8).
23. Mark 1 cell adjacent to stars as X (row 2, column 9).
24. Region completion: 1 star needed, 1 candidate (row 4, column 8).
25. Mark 2 cells adjacent to stars as X (row 4, column 9).
26. Column 4 complete: Mark 3 remaining cells as X (row 7, column 4).
27. Two last candidates (row 4): Eliminate 2 cells adjacent to both (row 5, column 1).
28. Row completion: 1 star needed, 1 candidate (row 5, column 3).
29. Mark 3 cells adjacent to stars as X (row 4, column 2).
30. Row completion: 1 star needed, 1 candidate (row 4, column 1).
31. Clump analysis (Column 2): candidate clumps can only just supply the remaining stars (row 8, column 1).
32. Two last candidates (column 3): Eliminate 1 cell adjacent to both (row 8, column 2).
33. Region confined to row: Eliminate other row candidates (row 9, column 9).
34. Three candidates in a column: Middle cell can't hold a star (row 7, column 9).
35. Region completion: 2 stars needed, 2 candidates (row 6, column 9).
36. Region completion: 1 star needed, 1 candidate (row 8, column 9).
37. Row 6 complete: Mark 1 remaining cell as X (row 6, column 1).
38. Row 8 complete: Mark 1 remaining cell as X (row 8, column 5).
39. Region completion: 1 star needed, 1 candidate (row 7, column 5).
40. Column 5 complete: Mark 1 remaining cell as X (row 9, column 5).
41. Three candidates in a row: Middle cell can't hold a star (row 9, column 2).
42. Region completion: 2 stars needed, 2 candidates (row 9, column 1).
43. Region completion: 1 star needed, 1 candidate (row 9, column 3).
44. Column 1 complete: Mark 1 remaining cell as X (row 7, column 1).
45. Column completion: 1 star needed, 1 candidate (row 7, column 2).
46. Mark 1 cell adjacent to stars as X (row 7, column 3).
47. Solved! Every row, column, and region has its two stars, none touching.