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