michaele wrote:

The key to solving this puzzle is to find cross pairs, if you work on looking for cross pairs the puzzle can be solved reasonably easily.

I don't know if cross pairs is the correct name to use, as an example of what I mean by a 'cross pair' in this puzzle cage a1(8:)=1&8 and cage h1(10|)=2&8, so rows 1 and 2 have 8 as a cross pair and no other cell can have a value of 8 in rows 1 and 2.

Sometimes cross pairs are obvious, but other times they can hide. It is worth the extra effort to find the cross pairs, they can make a big difference.

[…]

You probably mean an X-wing strategy – well known in the sudoku world.

And I agree, this strategy is very useful in this puzzle, especially “double” X-wing in the top two rows:

BC12 (#7) + EF12 (#6) eliminate G1 to candidates 4 and 5; 4 causes no position for 6 in the row 1, therefore G1 = 5, thus 8 in the column F must be placed in the row 7. The rest is already easier…