Hard Star Battle answer — December 28, 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. 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 1).
3. Three candidates with two adjacent: Isolated candidate must hold a star (row 9, column 1).
4. Mark 2 cells adjacent to stars as X (row 8, column 2).
5. Two-option rule: Cell adjacent to both candidates (row 6, column 1).
6. Two-option rule: Cell adjacent to both candidates (row 6, column 2).
7. Blocking rule: a star here would touch every other open cell in its region, leaving no room for the region's second star (row 4, column 6).
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 6, column 7).
9. Blocking rule: a star here would touch every other open cell in its region, leaving no room for the region's second star (row 4, column 1).
10. Blocking rule: a star here would touch every other open cell in its region, leaving no room for the region's second star (row 4, column 2).
11. Clump analysis (Region 2): candidate clumps can only just supply the remaining stars (row 2, column 6).
12. Clump analysis (Region 5): candidate clumps can only just supply the remaining stars (row 5, 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 6).
14. Three candidates with two adjacent: Isolated candidate must hold a star (row 3, column 5).
15. Mark 4 cells adjacent to stars as X (row 2, column 4).
16. Two-option rule: Cell adjacent to both candidates (row 3, column 8).
17. Two-option rule: Cell adjacent to both candidates (row 4, column 8).
18. Blocking rule: a star here would touch every other open cell in its region, leaving no room for the region's second star (row 2, column 8).
19. Clump analysis (Region 6): candidate clumps can only just supply the remaining stars (row 5, column 2).
20. Three candidates with two adjacent: Isolated candidate must hold a star (row 5, column 1).
21. Column 1 complete: Mark 4 remaining cells as X (row 1, column 1).
22. Region completion: 1 star needed, 1 candidate (row 7, column 2).
23. Mark 2 cells adjacent to stars as X (row 6, column 3).
24. Region completion: 1 star needed, 1 candidate (row 3, column 2).
25. Mark 4 cells adjacent to stars as X (row 2, column 2).
26. Row completion: 2 stars needed, 2 candidates (row 2, column 7).
27. Mark 4 cells adjacent to stars as X (row 1, column 6).
28. Region completion: 1 star needed, 1 candidate (row 4, column 7).
29. Mark 2 cells adjacent to stars as X (row 5, column 7).
30. Row completion: 1 star needed, 1 candidate (row 2, column 9).
31. Mark 2 cells adjacent to stars as X (row 1, column 9).
32. Row completion: 1 star needed, 1 candidate (row 4, column 9).
33. Mark 1 cell adjacent to stars as X (row 5, column 9).
34. Column 2 complete: Mark 1 remaining cell as X (row 1, column 2).
35. Column 7 complete: Mark 3 remaining cells as X (row 7, column 7).
36. Column 9 complete: Mark 4 remaining cells as X (row 6, column 9).
37. Three candidates in a row: Middle cell can't hold a star (row 1, column 4).
38. Region completion: 2 stars needed, 2 candidates (row 1, column 3).
39. Region completion: 1 star needed, 1 candidate (row 1, column 5).
40. Column 5 complete: Mark 5 remaining cells as X (row 5, column 5).
41. Row completion: 1 star needed, 1 candidate (row 5, column 3).
42. Mark 1 cell adjacent to stars as X (row 6, column 4).
43. Region completion: 1 star needed, 1 candidate (row 7, column 4).
44. Mark 1 cell adjacent to stars as X (row 8, column 4).
45. Row completion: 2 stars needed, 2 candidates (row 6, column 6).
46. Mark 1 cell adjacent to stars as X (row 7, column 6).
47. Row completion: 1 star needed, 1 candidate (row 6, column 8).
48. Mark 1 cell adjacent to stars as X (row 7, column 8).
49. Row completion: 2 stars needed, 2 candidates (row 8, column 6).
50. Mark 1 cell adjacent to stars as X (row 9, column 6).
51. Row completion: 1 star needed, 1 candidate (row 8, column 8).
52. Mark 1 cell adjacent to stars as X (row 9, column 8).
53. Column 3 complete: Mark 1 remaining cell as X (row 9, column 3).
54. Region completion: 1 star needed, 1 candidate (row 9, column 4).
55. Solved! Every row, column, and region has its two stars, none touching.