This was another real toughie. It took me quite a while to get a hook into it, although it fell into place after that. Be interesting to see how many people in total solve it.

DId you get the achievement?

Yes thanks.

Here is my method for solving this puzzle. I found it to be an interesting puzzle to solve.

1. Calculate cage values
b9=7,9
g6=6,8,9
i6=6,7,8,9

2. Add row 9
>> a9+d9=8
>> a9 & d9=2,3,5,6

3. Cage e9 must have 8, it is the only cage in row 9 that can have 8

4. g9,h9,i9 can not be 8 (refer to cages g6,i6: both g6 and i6 would be 8)
>> e9 or f9 must be 8

5. g7,g8,i7 can not be 6,8,9 (by adding cages in the 3x3 box e9+f9 would have to total 8)
>> i7=7

6. Using same method as step 5
g6 is not 9

7. Add columns f,g,h,i
>> e1,e7,e9 = 6,8,9

8. Add 3x3 box (g7:i9)
>> e9+f9=9
>> e9=8, f9=1

9. Calculate cage values
i2=6,9
i4=1,2,4,5
g5=2,4,7,9

10. Cage h5 must have 2 or 4
>> cage i4 can not be 2,4

11. Calculate cage values
h7=1,2,3,4,5,6
cage e9: g9=2,3,4,5 h9=3,4,5,6 i9=2,3,4

12. Calculate cage values
h3=2,3,7,8
(note in column h 1 must be in h7 or h8)

13. Cage g5 must be 2,9 (only cage with 9 in 3x3 box)

14. Calculate cage values
h3=3,7 (refer to cage h5)
e1 each cell can be all available values
b1 =4,5,6,7,8,9

15. g4 & g5=3,4,7 (note that g4 or g5=4)

16. Cage b2 is not 4,9 (cage e1 would have no possible values)
(note h2 would be 4 if cage b2=4,9)

17. Add row 1
>> a1+d1=h2+1
>> a1+d1=5,6 or 9
>> a1,d1=1,2,3,4,5,6,7,8

18. Add 3x3 box (a7:c9)
>> a7+c7+c8=8
a7=3,5 c7&c8=1,2,4
(note c7 or c8 must be 1)

19. In column d the only cell that could be 9 is d5

20. g5=2, g6=9, a6=7, a7=5
c7&c8=1,2

21. Add 3x3 box (d7:f9)
>> d7=c8+2
>> d7=3,4

22. d8,e8 or d9 must be 2
>> c8 is not 2
>> c7=2, d7=3, d6=4

From this point it is all basic steps to complete the puzzle.