Welcome to goooders but he/she clearly doesn't know the "netiquette" on this forum. One doesn't post a message like that while a puzzle is still active unless it's in tiny text; the first line is OK in normal text.
Ruud wrote:Although this Assassin cannot be solved by SumoCue, it only requires a single advanced move. Can you find it?
Maybe that was step 18?
This was a smooth puzzle except right at the end where I had to work harder to finish it off. Maybe I missed something there. Here is my walkthrough.
Thanks to Mike and Para for their comments which have been added below. The comment after step 33d and the typo corrections in steps 48 and 51 were made earlier.
1. R4C12 = {49/58/67}, no 1,2,3
2. R4C89 = {19/28/37/46}, no 5
3. R5C12 = {17/26/35}, no 4,8,9
4. R5C89 = {59/68}
5. R6C12 = {17/26/35}, no 4,8,9
6. R6C89 = {17/26/35}, no 4,8,9
7. R456C5 = 1{25/34}, 1 locked for C5 and N5
8. 45 rule on N1 2 outies R1C4 + R4C3 = 14 = {59/68/77}
8a. Min R1C4 = 5 -> max R1C23 = 8, no 8,9
9. 45 rule on N2 2 innies R1C46 = 8 = [53/62/71], clean-up: no 5,6 in R4C3 (step 8)
10. 45 rule on N3 2 outies R1C6 + R4C7 = 4 = {13/22}
11. 45 rule on N7 2 outies R6C3 + R9C4 = 6 = {15/24/33}
12. 45 rule on N8 2 innies R9C46 = 11 = [29/38/47/56], clean-up: no 5 in R6C3 (step 11)
13. 45 rule on N9 2 outies R6C7 + R9C6 = 17 = {89}, clean-up: no 4,5 in R9C4 (step 12), no 1,2 in R6C3 (step 11)
13a. Min R9C6 = 8 -> max R9C78 = 8, no 8,9
[Mike pointed out that after step 13 there is the CPE no 8,9 in R6C6. This then sets up a hidden pair {89} in R6C47 -> R6C4 = {89}.]
14. Killer pair 8,9 in R5C89 and R6C7, locked for N6, clean-up: no 1,2 in R4C89
15. 23(4) cage at R6C3 with R6C3 = {34} = {2489/3479/3569/3578/4568}, no 1
16. 45 rule on N5 2 outies R5C37 = 7 = {16/25/34}, no 7,8,9
17. R5C34567 must contain 4 and 8/9
17a. 45 rule on R5 5 innies R5C34567 = 23 = {13478/23459/23468} (cannot be {12479} which clashes with R5C37, cannot be {13469} which clashes with R5C89) = 34{178/259/268}, 3 locked for R5, clean-up: no 5 in R5C12
[Para pointed out that I missed R5C37 cannot be {16} because there are no R5C34567 combinations with both 1 and 6. Alternatively, and possibly more obvious, R5C37 cannot be {16} because this would clash with R5C12.]
18. Hidden killer pair 8,9 for N4 in R4C12 and R4C3 -> R4C12 = {49/58}, R4C3 = {89}, 8,9 locked for R4, clean-up: no 7 in R1C4 (step 8), no 1 in R1C6 (step 9), no 3 in R4C7 (step 10)
19. 7 in N4 must be in R5C12 or R6C12, one of which must be {17} -> no 1 in R5C3, clean-up: no 6 in R5C7 (step 16)
20. 45 rule on C123 2 outies R19C4 – 4 = 1 innie R5C3, min R19C4 = 7 -> min R5C3 = 3, clean-up: no 5 in R5C7 (step 16)
[Para pointed out that if I had done step 20 before step 19, then there would have been a hidden killer double instead of hidden killer singles. However this is the order in which I spotted the moves. The fact that we see different moves, or see the same moves in different orders, is one of the things that makes this forum interesting and makes it worthwhile working through other people’s walkthroughs.]
21. R5C12 must contain 1/2 -> R6C12 must contain 1/2 -> R6C12 = {17/26}, 6 locked in R56C12 for N4, clean-up: no 1 in R5C7 (step 16)
22. 3 in N4 locked in R56C3, locked for C3
23. 25(4) cage at R4C4 with R5C3 = {345} = {3589/3679/4579/4678}, no 2
23a. 19(4) cage at R4C6 = {2359/2368/2458/2467/3457}
24. 45 rule on R1 3 innies R1C159 = 19 = {289/379/469/478/568}, no 1
25. 45 rule on N6 3 innies R456C7 = 13 = [139/148/238] -> no 2 in R5C7, clean-up: no 5 in R5C3 (step 16)
26. Naked pair {34} in R5C37, locked for R5
27. Naked pair {34} in R56C3, locked for C3 and N4, clean-up: no 9 in R4C12
28. Naked pair {58} in R4C12, locked for R4 -> R4C3 = 9 -> R1C4 = 5 (step 8), R1C6 = 3 (step 9), R4C7 = 1 (step 10), clean-up: no 7 in R6C89
29. 7 in N6 locked in R4C89 = {37}, locked for R4 and N6 -> R5C7 = 4, R5C3 = 3, R6C3 = 4, R9C4 = 2 (step 11), R9C6 = 9 (step 12), R6C7 = 8 (step 13), clean-up: no 6 in R5C89, no 5 in R6C89
[Para “As i always check hidden singles. There is a hidden single 3 in R6C5 at this point. Doesn't matter much as it becomes naked in 2 steps.” Maybe I forgot to eliminate 3 from R6C4. It’s so easy to overlook those round-the-corner eliminations. In this puzzle I always remembered the ones for the L-shaped 4-cell cages but often forgot them for the sideways T-shaped cages, both when originally solving this puzzle and later when checking walkthroughs.]
30. Naked pair {26} in R6C89, locked for R6
31. Naked pair {17} in R6C12, locked for R6 and N4 -> R6C456 = [935]
32. R5C5 = 1 (hidden single in R5), R4C5 = 4 (cage sum), R4C46 = [62], R5C4 = 7 (cage sum), R5C6 = 8
33a. R1C4 = 5 -> R1C23 = 8 = {17/26}, no 4
33b. R1C6 = 3 -> R1C78 = 10 = [28/64/91]
33c. R9C4 = 2 -> R9C23 = 10 = [37/46]
33d. R9C6 = 9 -> R9C78 = 7 = [34/61]
[I missed R9C78 cannot be [34] which clashes with R9C23, as in goooders message and Para's walkthrough, but fortunately it didn’t matter as I fixed those cells with the next step.]
34. 5 in R9 locked in R9C159
34a. 45 rule on R9 3 innies R9C159 = 17 = {458} (only remaining combination), locked for R9 -> R9C23 = [37], R9C78 = [61], clean-up: no 1 in R1C2 (step 33a), no 4 in R1C8 (step 33b) -> R1C78 = [28], R1C23 = [71], R6C12 = [71]
35. 16(4) cage at R2C7 = {1357/1456} = 15{37/46}, no 9, 5 locked for N3
35a. 20(4) cage in N3 = 19{37/46}
[Para pointed out that {1456} is blocked because 4,6 only in R2C8. Oops!
I should have spotted that. It was getting very late when I finished this puzzle and first posted my walkthrough.]
36. 9 in C7 locked in R78C7, locked for N9
[Alternatively grouped X-Wing for 9 in 20(4) cage in N3 and R5C89, locked for C89, but I spotted the locked 9 in C7 first.]
37. 24(4) cage at R6C7 = {2589/3489} = 89{25/34}, no 7
37a. R78C7 = {359} -> R8C8 = {24}
38. 7 in C7 locked in R23C7, locked for N3
38a. 16(4) cage at R2C7 (step 35) = {1357} (only remaining combination), 3 locked for N3
39. 23(4) cage at R6C3 = {2489/4568} = 48{29/56}, 8 locked for N7
39a. 16(4) cage in N7 = 14{29/56}
40. 25(4) cage at R2C2 = {2689} (only remaining combination), 2,6,8 locked for N1
41. 5 in C3 locked in R78C3, locked for N7 -> R9C1 = 4, R1C159 = [964]
42. Naked pair {35} in R23C1, locked for C1 and N1 -> R3C2 = 4, R4C12 = [85]
43. 23(4) cage at R6C3 (step 39) = {4568} (only remaining combination), locked for N7
44. Naked pair {12} in R78C1, locked for C1 and N7 -> R5C12 = [62], R7C2 = 9
45. Naked triple {578} in R789C5, locked for C5 and N8
46. Naked pair {35} in R2C18, locked for R2 -> R2C7 = 7
47. R3C6 = 7 (hidden single in R3)
48. R8C7 = 9 (hidden single in
C7)
49. R7C456 = [186/384/456] (cannot be {357} which clashes with R7C7), no 7 in R7C5, no 1 in R7C6
50. R8C5 = 7 (hidden single in C5)
51. 19(4) cage at R8C5 = [1765/3718/3745], no 4 in R8C
4
52. 22(4) cage in N9 = {2578/3478} = 78{25/34}
52a. For {3478} 4 must be in R7C8 and 7 in R7C9 -> no 3 in R7C89
53. 20(4) cage at R1C5 = {1469} (only remaining combination because [6824] clashes with R2C23) -> R2C5 = 9, R2C46 = {14}, locked for R2 and N2
and the rest is naked singles, hidden singles and cage sums