Samurai X – HNY!
Samurai X for New Year’s Day – this is the only place you can find these kind of Sudoku puzzles!
Warning: Today’s puzzle is the MOST difficult Samurai X yet!
Basically, not only do you have to fight against 5 interconnected Sudokus, but you also need to be carefull about the diagonals: ALL diagonals in the puzzle must contain one occurrence of each 1-9 digit. The diagonals are marked in the puzzle so you wouldn’t forget about them.
By clicking on this thumbnail a download will start which will give you the full puzzle.
Click here to download the solution
UPDATE: Download this file to see the solution up to the critical point, when you must use “X-Wing” (for number 5 in the upper left sub-puzzle), which indirectly solves one cell and after that it should be relatively easy to do (no fancy stuff required).
I warned you – this was an extremely difficult puzzle 
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Killer Sudoku fans
January 7th, 2006 at 12:44 pm
To solve this one do we need any special technique or is it business as usual?
Best regards.
Fernando Castro
January 7th, 2006 at 1:10 pm
Fernando, this one is extremely difficult because it requires X-Wing to solve.
Hint: X-Wing is for number 5 in the upper-left 9×9 sub-Sudoku.
January 9th, 2006 at 5:46 pm
Another Samurai solver program has told me this is not solvable! I certainly couldn’t solve it.
January 9th, 2006 at 6:05 pm
Sue, as far as i know there are no other Samurai programs that can handle Samurai “X”, which means that the diagonals must also contain all numbers 1-9.
If you don’t take that into consideration, then there are probably multiple solutions.
I will upload an image showing the position up to the critical move required to solve this puzzle.
January 10th, 2006 at 4:27 pm
I have finally solved the Samurai X – HNY however I came back to the site as the only way I found to solve it was to run two alternatives until it became clear which worked. Oddly (before having looked at your tip) I chose the 5-9 combination from the right column of the top left puzzle as the two alternatives. 5 in the lower of the two quickly produced an error which left 9 as the key to the rest of the solution. The whole puzzle then took no more than an hour or so to solve. I was curious as to why I couldn’t see a logical solution and saw your tip to use x-wing. Having looked at the x-wing method I am still none the wiser, what am I missing? Many thanks though for a thoroughly frustrating puzzle.