Prelims
a) R23C1 = {89}
b) R23C4 = {79}
c) R5C67 = {18/27/36/45}, no 9
d) R6C67 = {14/23}
e) 10(2) cage at R7C2 = {19/28/37/46}, no 5
e) R7C67 = {49/58/67}, no 1,2,3
f) R9C78 = {29/38/47/56}, no 1
g) 9(3) cage at R2C5 = {126/135/234}, no 7,8,9
h) 10(3) cage at R7C3 = {127/136/145/235}, no 8,9
i) 18(5) cage at R2C3 = {12348/12357/12456}, no 9
1a. Naked pair {89} in R23C1, locked for C1 and N1, clean-up: no 1,2 in R7C2
1b. Naked pair {79} in R23C4, locked for C4 and N2
1c. 9 in R1 only in R1C789, locked for N3
1d. 15(3) cage at R1C1 = {267/357/456}, no 1
1e. 1 in N1 only in R23C23, CPE no 1 in R45C2
1f. 18(5) cage at R2C3 = {12348/12357/12456}, 1 locked for C3
1g. 18(5) cage at R2C3 = {12348/12357/12456}, CPE no 2 in R56C3
1h. 10(3) cage at R7C3 = {127/136/145/235}
1i. 1 of {136/145} must be in R7C4 -> no 4,6 in R7C4
1j. 45 rule on N3 2 outies R4C79 = 15 = {69/78}
1k. 45 rule on C9 2 innies R56C9 = 7 = {16/25/34}, no 7,8,9
1l. 45 rule on C89 2 innies R89C8 = 6 = [15]/{24} -> R9C7 = {679}
1m. 45 rule on N14 2 outies R6C4 + R7C1 = 11 = [47/56/65/83]
1n. 45 rule on R789 2 innies R7C18 = 11 = [38/56/65/74]
1o. 45 rule on N5 2 outies R56C7 = 1 innie R6C4 + 2, IOU no 2 in R5C7, clean-up: no 7 in R5C6
1p. Min R6C4 = 4 -> min R56C7 = 6, max R6C7 = 4 -> no 1 in R5C7, clean-up: no 8 in R5C6
1q. 45 rule on N7 2 innies R7C1 + R9C3 = 1 outie R7C4 + 10
1r. Min R7C1 + R9C3 = 11, max R7C1 = 7 -> min R9C3 = 4
1s. 9 in N4 only in 33(6) cage at R5C3 = {135789/145689/234789/235689/245679} (cannot be {126789} which clashes with R6C67)
1t. Killer pair 1,2 in 33(6) cage and R6C67, locked for R6, clean-up: no 5,6 in R5C9
1u. Consider combinations for R7C18 = [38/56/65/74]
R7C18 = [38] => 10(3) cage at R7C3 = {127/145} => R7C4 = 1
or R7C18 = {56}, locked for R7
or R7C18 = [74] => R7C67 = {58}, 5 locked for R7
-> no 5 in R7C4
[Now I was running out of ideas so did some fairly heavy combination analysis, something I try to avoid doing these days.]
2a. 28(6) cage at R4C8 = {123589/134569/134578/234568} (cannot be {123679} which clashes with R4C79, cannot be {124579} = {1479}{25} which clashes with R89C8, cannot {124678} = {2478}{16} which clashes with R4C79), 3 locked for N6, clean-up: no 6 in R5C6, no 2 in R6C6
2b. 28(6) cage = {1389}[25]/{1569}{34}/{1578}{34}/{3468}[25] (cannot be {3459}[16]/{2568}{34} which clash with R89C8), no 2 in R45C8, no 1 in R5C9, no 6 in R6C9
2c. 4 of {134569/134578} is in R56C9, 4 of {234568} must be in R456C8 (cannot be {368}[25]4 which clashes with R4C79) -> no 4 in R7C8, clean-up: no 7 in R7C1 (step 1n), no 4 in R6C4 (step 1m)
2d. Killer pair 1,4 in 28(6) cage and R89C8, locked for C8
2e. 18(3) cage at R1C8 = {279/369/378/567}
2f. 9 of {279} must be in R1C8 -> no 2 in R1C8
2g. Consider placement for 2 in N6
2 in R5C9
or 2 in R6C7 => R6C6 = 3, R6C9 = 4
-> R56C9 = [25/34]
2h. 45 rule on N5 3 innies R5C6 + R6C46 = 12 = {138/345} (cannot be {156} = [561] because 9(2) cage at R5C6 is 4 more than 5(2) cage at R6C6), cannot be {246} = [264] which clashes with R56C9), no 2,6, 3 locked for C6 and N5, clean-up: no 7 in R5C7, no 5 in R7C1 (step 1m), no 6 in R7C8 (step 1n)
2i. R6C4 = {58} -> no 5 in R5C6, no 4 in R5C7
2j. 10(3) cage at R7C3 = {127/145/235} (cannot be {136} which clashes with R7C1), no 6
2k. R7C67 = {49/67} (cannot be {58} which clashes with R7C8), no 5,8
2l. R56C6 = {13/34} -> R56C7 must contain one of 2,6
2m. 28(6) cage = {1389}[25]/{1569}{34}/{1578}{34} (cannot be {3468}[25] which clashes with R56C7), 1 locked for C8 and N6, clean-up: no 4 in R6C6, no 5 in R9C8 (step 1l), no 6 in R9C7
2n. Naked pair {24} in R89C8, locked for C8 and N9, clean-up: no 9 in R7C6
2o. Naked pair {24} in R89C8, CPE no 2,4 in R9C6
2p. 4 in N6 only in R6C79, locked for R6
2q. 15(3) cage at R7C9 = {159/168} (cannot be {357} which clashes with R56C9), no 3,7, 1 locked for C9 and N9
2r. R8C7 = 3 (hidden single in N9), clean-up: no 7 in R7C2
2s. 7 in N9 only in R79C7, locked for C7, clean-up: no 8 in R4C9 (step 1j)
2t. Max R8C78 = 7 -> min R89C6 = 12, no 1,2 in R89C6
3a. Consider combination for R7C67 = [49]/{67}
R7C67 = [49] => R56C6 = {13}, R6C4 = 8 (step 2h) => R7C1 = 3 (step 1m)
or R7C67 = {67}, 6 locked for R7
-> R7C1 = 3, R6C4 = 8 (step 1m), R56C6 = {13} (step 2h), 1 locked for C6 and N5, clean-up: no 5 in R5C7, no 7 in R8C1
[Cracked, the rest is fairly straightforward]
3b. 10(3) cage at R7C3 (step 2j) = {127/145} -> R7C4 = 1
3c. R7C4 = 1 -> R7C1 + R9C3 = 11 (step 1q), R7C1 = 3 -> R9C3 = 8, R9C45 = 5 = {23}, locked for R9 and N8, R9C8 = 4 -> R9C7 = 7, R8C8 = 2, clean-up: no 6 in R7C6
3d. R7C3 = 2 (hidden single in N7) -> R8C3 = 7 (cage sum)
3e. R7C1 = 3 -> R7C8 = 8 (step 1n) -> 15(3) cage at R7C9 (step 2q) = {159}, 5,9 locked for C9, 9 locked for N9, R7C7 = 6 -> R7C6 = 7, clean-up: no 4 in R8C1
3f. R6C79 = [24] -> R6C6 = 3, R5C679 = [183], R4C7 = 9 -> R4C9 = 6 (step 1j)
3g. Naked triple {157} in R456C8, 5,7 locked for C8
3h. 1 in R6 only in R6C12, locked for N4
3i. 1 in C3 only in R23C3, locked for N1
4a. R6C4 + R7C1 = [38], 1,9 in N4 only in 33(6) cage at R5C3 -> {135789} (only possible combination), 7 locked for R6 and N4 -> R56C8 = [75], R56C3 = [59], R6C5 = 6, R5C5 = 9 (hidden single in N5)
4b. 18(3) cage at R7C5 = {468} (only remaining combination) -> R7C5 = 4, R8C45 = [68], R7C2 = 9, R8C1 = 1, R6C12 = [71]
4c. Naked pair {56} in R9C12, 5 locked for R9 and N7 -> R8C2 = 4, R89C6 = [59]
4d. Naked pair {24} in R4C16, locked for R4 -> R4C2345 = [8357]
4e. R4C23 = [83] = 11 -> R23C3 + R5C2 = 7 = {124} -> R23C3 = {14}, 4 locked for N1, R5C2 = 2
4f. R45C1 = [46] = 10 -> R23C2 = 8 = {35}, locked for N1, R4C6 = 2
4g. 15(3) cage at R1C1 = [276] -> R1C69 = [48]
4h. R3C6 = 6 -> R23C5 = 3 = {12}, locked for C5
and the rest is naked singles.