Thanks Børge for your first Assassins! I decided to start with the easier one and enjoyed it; even though it has a low SS score I still had to think hard at one stage so it's definitely an Assassin.
After the first two placements the "arrow into the heart" was very helpful for the next three placements.
Here is my walkthrough for A178 V0.75.
Thanks Afmob for pointing out that there was an error at the beginning of the original step 14; I've re-worked steps 14 and 15 and also made a few minor corrections and clarifications to earlier steps.Prelims
a) 11(2) cage in N1 = {29/38/47/56}, no 1
b) R1C34 = {14/23}
c) R1C67 = (18/27/36/45}, no 9
d) 10(2) cage in N3 = {19/28/37/46}, no 5
e) R2C34 = {14/23}
f) R2C67 = {39/48/57}, no 1,2,6
g) R34C1 = {49/58/67}, no 1,2,3
h) 6(2) cage at R3C3 = {15/24}
i) 13(2) cage at R3C7 = {49/58/67}, no 1,2,3
j) R34C9 = {16/25/34}, no 7,8,9
k) R67C1 = {14/23}
l) 11(2) cage at R6C2 = {29/38/47/56}, no 1
m) 13(2) cage at R6C8 = {49/58/67}, no 1,2,3
n) R67C9 = {17/26/35}, no 4,8,9
o) 4(2) cage in N7 = {13}
p) R8C34 = {29/38/47/56}, no 1
q) R8C67 = {19/28/37/46}, no 5
r) 8(2) cage in N9 = {17/26/35}, no 4,8,9
s) R9C34 = {59/68}
t) R9C67 = {16/25/34}, no 7,8,9
u) 21(3) cage in N1 = {489/579/678}, no 1,2,3
v) 24(3) cage at R1C5 = {789}
w) 20(3) cage in N7 = {389/479/569/578}, no 1,2
x) 10(3) cage at R7C5 = {127/136/145/235}, no 8,9
Steps resulting from Prelims
1a. 4(2) cage in N7 = {13}, locked for N7, clean-up: no 2,4 in R6C1, no 8 in R6C2, no 8 in R8C4
1b. 24(3) cage at R1C5 = {789}, locked for C5 and N2, clean-up: no 1,2 in R1C7, no 3,4,5 in R2C7
1c. Naked pair {13} in R69C1, locked for C1, clean-up: no 8 in R2C2
1d. 1 in N1 locked in R123C3, locked for C3
2. 45 rule on C1234 1 innie R5C4 = 3, clean-up: no 2 in R12C3, no 8 in R8C3
2a. 45 rule on R6789 1 innie R6C5 = 6, clean-up: no 5 in R7C3, no 7 in R7C7, no 2 in R7C9
2b. 45 rule on C5 2 remaining innies R45C5 = 5 = {14}, locked for C5 and N5
2c. 45 rule on R1234 1 outie R5C5 = 1 innie R4C5 + 3 -> R5C5 = 4, R4C5 = 1, R5C6 = 8 (cage sum), clean-up: no 5 in R3C3, no 6 in R3C9, no 2 in R8C7
2d. Naked triple {235} in R789C5, locked for N8, clean-up: no 6,9 in R8C3, no 7,8 in R8C7, no 9 in R9C3, no 2,4,5 in R9C7
3. 16(4) cage at R3C6 = 4{129/156/237} (cannot be
4{138} because R4C6 only contains 2,5,7,9), no 8
3a. 1 of 4{129/156} must be in R3C6, only 2,3 of 4{237} can be in R3C6 -> R3C6 = {123}
3b. 6 of 4{156} must be in R4C7 -> no 5 in R4C7
4. 45 rule on R12 3 outies R3C258 = 20 = {389/479/569/578}, no 1,2
5. 45 rule on C12 3 outies R357C3 = 16
5a. Max R3C3 = 4 -> min R57C3 =
12, no 2,4 (R7C3 cannot be 4 because no 8 in R5C3), clean-up: no 7,9 in R6C2
6. 45 rule on C12 2 innies R46C2 = 1 outie R5C3 + 1
6a. Max R46C2 = 9 -> no 9 in R5C3
7. 18(3) cage at R3C4 = {189/279/369/459/567} (
cannot be {378} because no 3,7,8 in R3C4, cannot be {468} because no 4,6,8 in R4C4)
7a. 2 of {279} must be in R3C4 -> no 2 in R4C34
8. 45 rule on R89 3 outies R7C258 = 12 = {129/138/156/237/345} (cannot be {147} because R7C5 only contains 2,3,5, cannot be {246} which clashes with R7C1)
8a. Min R7C25 = 6 -> max R7C8 = 6
8b. 1 of {156} must be in R7C8 -> no 6 in R7C8
9. 45 rule on N7 4 innies R7C13 + R89C3 = 21 = {2469/2478/2568}
9a. 2,4 of {2478} must be in R7C1 + R8C3 -> no 7 in R
8C3, clean-up: no 4 in R8C
49b. 5 of {2568} must be in R8C3 -> no 5 in R9C3, clean-up: no 9 in R9C4
10. Naked pair {68} in R9C34, locked for R9, clean-up: no 1 in R9C67, no 2 in R8C8
11. R9C67 = [43], clean-up: no 6 in R1C6, no 5 in R1C7, no 8 in R2C7,
no 5 in R6C9, no 7 in R8C6, no 6 in R8C7, no 5 in
8(2) cage in N912. R3C4 = 6 (hidden single in N2) , R9C34 = [68], clean-up: no 7 in R4C1, no 7 in R4C8, no 5 in R6C2, no 5 in R8C3
12a. R4C34 = 12 = [39/57/75], no 4,8,9 in R4C3
13. R67C3 = {89} (hidden pair in C3), CPE no 9 in R7C4, clean-up: no 4 in R6C2
14. R45C3 = {57} (hidden pair in C3), locked for N4, clean-up: no 1 in R3C3, no 9 in R4C4 (step 12a)
14a. Naked pair {57} in R4C34, locked for R4, clean-up: no 8 in R3C7, no 2 in R3C9
14b. Naked pair {24} in R38C3, locked for C3, clean-up: no 1 in R12C4
14c. Naked pair {24} in R12C4, locked for C4 and N2, clean-up: no 7 in R1C7
14d. Naked pair {24} in 6(2) cage at R3C3, CPE no 4 in R3C2
14e. Naked triple {135} in R123C6, locked for C6, clean-up: no 9 in R8C7
15. R7C4 = 1 (hidden single in C4), R6C34 = 17 = [89], R7C3 = 9, R6C2 = 2, R4C2 = 4, R3C3 = 2, R8C34 = [47], R4C34 = [75], R4C6 = 2, R67C6 = [76], R6C7 = 4 (cage sum), R8C67 = [91], R6C8 = 5, R7C7 = 8, R7C1 = 2, R6C1 = 3, R5C3 = 5, R9C1 = 1, R8C2 = 3, R7C8 = 4, R8C8 = 6, R9C9 = 2, clean-up: no 7,8,9 in R1C1, no 1,5 in R1C6, no 4,6 in R1C9, no 9 in R2C2, no 8 in R2C8, no 5,8,9 in R3C1, no 7,9 in R3C7, no 3,5 in R3C9, no 9 in R4C8, no 5 in R7C9and the rest is naked singles and a cage sum.