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