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