That was a great puzzle nd, a tough challenge! Really neat key moves; the use of the 45 rule on r789 and the interactions in n2 as a result of r8c5 = {56}.
For those who haven't come across nd's earlier puzzles, they can be found at http://www.ndorward.com/blog/?page_id=71 As he says at the top of that page, they are all pretty difficult.
Congratulations to Ed and Peter for solving it; my contribution was very small - hope I can find time to make more contributions to the next team effort.
BTW Peter, Ed's step 56 is correct. Whichever of 6 or 8 is being considered for r1c3 blocks 6 or 8 for r1c6 so r1c6 = 4 follows. Ed has now added comments on this step.
A new one
Glad you enjoyed the puzzle! -- The {56} thing was really the turning point for getting it done (in that it's the point in the puzzle where all the hard work on N789 pays off & starts to have an effect on the rest of the grid); I'd been trying a different approach before & it never worked out. The other bit I liked (& it actually comes out more neatly in the final puzzle than in how I initially worked it out) is the {123} triplet in N4, which uses the properties of extra-long cages: this is one reason why I like large cages (as in puzzle #9).
Will try to get another puzzle or two done shortly--I have two in starting drafts, with the initial keys worked out.
Will try to get another puzzle or two done shortly--I have two in starting drafts, with the initial keys worked out.