Hard Star Battle answer — August 26, 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 8, column 2).
3. Region completion: 2 stars needed, 2 candidates (row 7, column 2).
4. Mark 7 cells adjacent to stars as X (row 6, column 1).
5. Region completion: 1 star needed, 1 candidate (row 9, column 2).
6. Mark 2 cells adjacent to stars as X (row 9, column 1).
7. Column 2 complete: Mark 5 remaining cells as X (row 1, column 2).
8. Blocking rule: a star here would touch every other open cell in its region, leaving no room for the region's second star (row 5, column 6).
9. Three candidates with two adjacent: Isolated candidate must hold a star (row 6, column 6).
10. Mark 7 cells adjacent to stars as X (row 5, column 5).
11. Region completion: 1 star needed, 1 candidate (row 4, column 7).
12. Mark 6 cells adjacent to stars as X (row 3, column 6).
13. Blocking rule: a star here would touch every other open cell in its region, leaving no room for the region's second star (row 3, column 4).
14. Blocking rule: a star here would touch every other open cell in its region, leaving no room for the region's second star (row 8, column 4).
15. Three candidates with two adjacent: Isolated candidate must hold a star (row 7, column 4).
16. Mark 2 cells adjacent to stars as X (row 6, column 4).
17. Row 7 complete: Mark 2 remaining cells as X (row 7, column 8).
18. Two last candidates (row 6): Eliminate 1 cell adjacent to both (row 5, column 9).
19. Clump analysis (Row 5): candidate clumps can only just supply the remaining stars (row 4, column 3).
20. Column completion: 2 stars needed, 2 candidates (row 1, column 1).
21. Column completion: 1 star needed, 1 candidate (row 5, column 1).
22. Clump analysis (Row 8): candidate clumps can only just supply the remaining stars (row 9, column 6).
23. Three candidates with two adjacent: Isolated candidate must hold a star (row 6, column 8).
24. Mark 1 cell adjacent to stars as X (row 6, column 9).
25. Clump analysis (Region 9): candidate clumps can only just supply the remaining stars (row 2, column 4).
26. Clump analysis (Region 2): candidate clumps can only just supply the remaining stars (row 3, column 9).
27. Row completion: 2 stars needed, 2 candidates (row 3, column 3).
28. Row completion: 1 star needed, 1 candidate (row 3, column 5).
29. Mark 2 cells adjacent to stars as X (row 2, column 6).
30. Row completion: 1 star needed, 1 candidate (row 4, column 9).
31. Column completion: 1 star needed, 1 candidate (row 8, column 6).
32. Mark 2 cells adjacent to stars as X (row 8, column 7).
33. Region completion: 1 star needed, 1 candidate (row 9, column 4).
34. Column 4 complete: Mark 2 remaining cells as X (row 1, column 4).
35. Region completion: 1 star needed, 1 candidate (row 5, column 3).
36. Column 3 complete: Mark 1 remaining cell as X (row 1, column 3).
37. Region completion: 1 star needed, 1 candidate (row 1, column 5).
38. Column completion: 1 star needed, 1 candidate (row 2, column 7).
39. Mark 1 cell adjacent to stars as X (row 2, column 8).
40. Region completion: 1 star needed, 1 candidate (row 2, column 9).
41. Column completion: 1 star needed, 1 candidate (row 8, column 8).
42. Mark 1 cell adjacent to stars as X (row 8, column 9).
43. Solved! Every row, column, and region has its two stars, none touching.