Hard Star Battle answer — August 29, 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 1).
3. Region completion: 2 stars needed, 2 candidates (row 1, column 1).
4. Mark 2 cells adjacent to stars as X (row 1, column 2).
5. Region completion: 1 star needed, 1 candidate (row 3, column 1).
6. Mark 3 cells adjacent to stars as X (row 3, column 2).
7. Column 1 complete: Mark 5 remaining cells as X (row 5, column 1).
8. Three candidates with two adjacent: Isolated candidate must hold a star (row 7, column 2).
9. Mark 5 cells adjacent to stars as X (row 6, column 2).
10. Region completion: 1 star needed, 1 candidate (row 5, column 2).
11. Mark 2 cells adjacent to stars as X (row 4, column 3).
12. Column 2 complete: Mark 1 remaining cell as X (row 9, column 2).
13. Three candidates with two adjacent: Isolated candidate must hold a star (row 9, column 5).
14. Mark 5 cells adjacent to stars as X (row 8, column 4).
15. Region completion: 1 star needed, 1 candidate (row 9, column 3).
16. Row 9 complete: Mark 3 remaining cells as X (row 9, column 7).
17. Three candidates in a row: Middle cell can't hold a star (row 8, column 8).
18. Row completion: 2 stars needed, 2 candidates (row 8, column 7).
19. Mark 3 cells adjacent to stars as X (row 7, column 6).
20. Region completion: 1 star needed, 1 candidate (row 8, column 9).
21. Mark 1 cell adjacent to stars as X (row 7, column 9).
22. 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 8).
23. Two last candidates (row 7): Eliminate 2 cells adjacent to both (row 6, column 4).
24. Clump analysis (Row 6): candidate clumps can only just supply the remaining stars (row 5, column 6).
25. Row completion: 1 star needed, 1 candidate (row 5, column 4).
26. Mark 2 cells adjacent to stars as X (row 4, column 4).
27. Row completion: 2 stars needed, 2 candidates (row 4, column 7).
28. Mark 2 cells adjacent to stars as X (row 3, column 6).
29. Row completion: 1 star needed, 1 candidate (row 4, column 9).
30. Mark 1 cell adjacent to stars as X (row 3, column 9).
31. Region complete: Mark 1 remaining cell as X (row 2, column 9).
32. Row completion: 1 star needed, 1 candidate (row 7, column 4).
33. Region complete: Mark 1 remaining cell as X (row 3, column 4).
34. Column 4 complete: Mark 2 remaining cells as X (row 1, column 4).
35. Column 7 complete: Mark 3 remaining cells as X (row 1, column 7).
36. Column 9 complete: Mark 2 remaining cells as X (row 1, column 9).
37. Region completion: 2 stars needed, 2 candidates (row 6, column 6).
38. Region completion: 1 star needed, 1 candidate (row 6, column 8).
39. Three candidates with two adjacent: Isolated candidate must hold a star (row 1, column 6).
40. Mark 3 cells adjacent to stars as X (row 1, column 5).
41. Row 1 complete: Mark 2 remaining cells as X (row 1, column 3).
42. Region completion: 1 star needed, 1 candidate (row 2, column 8).
43. Row completion: 1 star needed, 1 candidate (row 2, column 3).
44. Mark 1 cell adjacent to stars as X (row 3, column 3).
45. Region completion: 1 star needed, 1 candidate (row 3, column 5).
46. Solved! Every row, column, and region has its two stars, none touching.