Hard Star Battle answer — September 7, 2026

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 4).
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 9, column 5).
4. Clump analysis (Region 1): candidate clumps can only just supply the remaining stars (row 2, column 6).
5. Clump analysis (Region 6): candidate clumps can only just supply the remaining stars (row 9, column 7).
6. Clump analysis (Region 8): candidate clumps can only just supply the remaining stars (row 9, column 2).
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 9, column 6).
8. Three candidates with two adjacent: Isolated candidate must hold a star (row 10, column 6).
9. Mark 1 cell adjacent to stars as X (row 10, column 7).
10. Two-option rule: Cell adjacent to both candidates (row 7, column 5).
11. Two-option rule: Cell adjacent to both candidates (row 7, column 6).
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 7, column 7).
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 7, column 8).
14. Three candidates with two adjacent: Isolated candidate must hold a star (row 6, column 8).
15. Mark 6 cells adjacent to stars as X (row 5, column 7).
16. Two-option rule: Cell adjacent to both candidates (row 9, column 8).
17. Blocking rule: a star here would touch every other open cell in its region, leaving no room for the region's second star (row 3, column 6).
18. Star claim: Region 10 must place a star in row 4; cells touching all its options are eliminated (row 5, column 6).
19. Star claim: Region 10 must place a star in column 7; cells touching all its options are eliminated (row 3, column 7).
20. Crowding (Row 9): a star here would leave too little room for its 2 remaining stars (row 8, column 2).
21. Undercounting: 7 regions fit in cols 1-7, eliminate 3 outside candidates (row 1, column 6).
22. Region completion: 1 star needed, 1 candidate (row 8, column 8).
23. Mark 2 cells adjacent to stars as X (row 8, column 9).
24. Column completion: 2 stars needed, 2 candidates (row 2, column 7).
25. Mark 2 cells adjacent to stars as X (row 1, column 8).
26. Column completion: 1 star needed, 1 candidate (row 4, column 7).
27. Mark 2 cells adjacent to stars as X (row 4, column 6).
28. Region complete: Mark 1 remaining cell as X (row 4, column 5).
29. Column 8 complete: Mark 1 remaining cell as X (row 10, column 8).
30. 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 9).
31. 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 10).
32. Three candidates with two adjacent: Isolated candidate must hold a star (row 3, column 10).
33. Mark 3 cells adjacent to stars as X (row 3, column 9).
34. Column completion: 2 stars needed, 2 candidates (row 1, column 9).
35. Mark 1 cell adjacent to stars as X (row 1, column 10).
36. Column completion: 1 star needed, 1 candidate (row 10, column 9).
37. Mark 2 cells adjacent to stars as X (row 9, column 10).
38. Row completion: 2 stars needed, 2 candidates (row 9, column 1).
39. Mark 2 cells adjacent to stars as X (row 8, column 1).
40. Row completion: 1 star needed, 1 candidate (row 9, column 3).
41. Mark 4 cells adjacent to stars as X (row 8, column 3).
42. Clump analysis (Region 4): candidate clumps can only just supply the remaining stars (row 6, column 2).
43. Clump analysis (Region 6): candidate clumps can only just supply the remaining stars (row 8, column 10).
44. Generalized counting (rows 5-7): region star limits exclude these cells (row 4, column 4).
45. Row completion: 1 star needed, 1 candidate (row 4, column 1).
46. Mark 4 cells adjacent to stars as X (row 3, column 1).
47. Column 1 complete: Mark 4 remaining cells as X (row 1, column 1).
48. Region completion: 2 stars needed, 2 candidates (row 5, column 3).
49. Mark 3 cells adjacent to stars as X (row 5, column 4).
50. Region completion: 1 star needed, 1 candidate (row 7, column 2).
51. Mark 1 cell adjacent to stars as X (row 7, column 3).
52. Column 3 complete: Mark 3 remaining cells as X (row 1, column 3).
53. Row completion: 1 star needed, 1 candidate (row 3, column 5).
54. Mark 1 cell adjacent to stars as X (row 2, column 5).
55. Row completion: 1 star needed, 1 candidate (row 2, column 2).
56. Mark 1 cell adjacent to stars as X (row 1, column 2).
57. Column completion: 2 stars needed, 2 candidates (row 1, column 4).
58. Mark 1 cell adjacent to stars as X (row 1, column 5).
59. Column completion: 1 star needed, 1 candidate (row 7, column 4).
60. Mark 2 cells adjacent to stars as X (row 6, column 5).
61. Region completion: 1 star needed, 1 candidate (row 8, column 6).
62. Row 7 complete: Mark 1 remaining cell as X (row 7, column 10).
63. Column completion: 1 star needed, 1 candidate (row 5, column 5).
64. Mark 1 cell adjacent to stars as X (row 6, column 6).
65. Row 5 complete: Mark 1 remaining cell as X (row 5, column 10).
66. Region completion: 1 star needed, 1 candidate (row 6, column 10).
67. Solved! Every row, column, and region has its two stars, none touching.