Hard Star Battle answer — December 31, 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 7, column 3).
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 7, column 4).
6. Mark 5 cells adjacent to stars as X (row 6, column 4).
7. Row 7 complete: Mark 4 remaining cells as X (row 7, 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 8, 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 9, column 7).
10. Clump analysis (Row 6): candidate clumps can only just supply the remaining stars (row 5, column 6).
11. Clump analysis (Row 5): candidate clumps can only just supply the remaining stars (row 4, column 2).
12. Clump analysis (Row 8): candidate clumps can only just supply the remaining stars (row 9, column 8).
13. Three candidates with two adjacent: Isolated candidate must hold a star (row 8, column 8).
14. Mark 1 cell adjacent to stars as X (row 8, column 9).
15. Row completion: 1 star needed, 1 candidate (row 8, column 6).
16. Mark 2 cells adjacent to stars as X (row 9, column 5).
17. Three candidates with two adjacent: Isolated candidate must hold a star (row 9, column 4).
18. Mark 1 cell adjacent to stars as X (row 9, column 3).
19. Region completion: 1 star needed, 1 candidate (row 9, column 2).
20. Mark 1 cell adjacent to stars as X (row 9, column 1).
21. Column 2 complete: Mark 4 remaining cells as X (row 1, column 2).
22. Column 4 complete: Mark 4 remaining cells as X (row 1, column 4).
23. Three candidates with two adjacent: Isolated candidate must hold a star (row 5, column 3).
24. Mark 1 cell adjacent to stars as X (row 4, column 3).
25. Clump analysis (Column 3): each clump must supply its full share of stars (row 1, column 1).
26. Mark 1 cell adjacent to stars as X (row 2, column 1).
27. Clump analysis (Column 5): candidate clumps can only just supply the remaining stars (row 2, column 6).
28. Clump analysis (Region 8): candidate clumps can only just supply the remaining stars (row 2, column 7).
29. Clump analysis (Row 1): each clump must supply its full share of stars (row 2, column 5).
30. Mark 4 cells adjacent to stars as X (row 1, column 5).
31. Column completion: 1 star needed, 1 candidate (row 6, column 6).
32. Mark 2 cells adjacent to stars as X (row 5, column 5).
33. Row completion: 1 star needed, 1 candidate (row 5, column 1).
34. Mark 1 cell adjacent to stars as X (row 4, column 1).
35. Column 1 complete: Mark 1 remaining cell as X (row 3, column 1).
36. Region completion: 1 star needed, 1 candidate (row 4, column 5).
37. Three candidates with two adjacent: Isolated candidate must hold a star (row 4, column 9).
38. Mark 3 cells adjacent to stars as X (row 3, column 8).
39. Row completion: 2 stars needed, 2 candidates (row 3, column 3).
40. Mark 1 cell adjacent to stars as X (row 2, column 3).
41. Row completion: 1 star needed, 1 candidate (row 2, column 9).
42. Mark 1 cell adjacent to stars as X (row 1, column 8).
43. Region completion: 1 star needed, 1 candidate (row 1, column 7).
44. Row completion: 1 star needed, 1 candidate (row 3, column 7).
45. Mark 1 cell adjacent to stars as X (row 4, column 7).
46. Column completion: 1 star needed, 1 candidate (row 6, column 8).
47. Mark 1 cell adjacent to stars as X (row 6, column 9).
48. Solved! Every row, column, and region has its two stars, none touching.