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