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