Extra special – Butterfly Killer Sudoku (hard)

Somehow butterfly puzzles have been neglected in the past few months and it’s time to rectify. A quick reminder – this breed of overlapping sudoku puzzles was suggested by udosuk and implemented by myself. There are 4 “classic” 9×9 Killer Sudoku puzzles inside this one. They all overlap and they all must be solved according to the rules of Sudoku. You can (in fact, you must) use the Twin Nonets solving technique for this one!
(click to download or right-click to save the image!)

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sudoku variants and other puzzle books
To see the solution to this puzzle click here
Have fun!
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  1. Sandra
    Posted July 31, 2006 at 1:13 pm | Permalink

    I’ve tried downloading this puzzle a few times but all I get is an ordinary killer. Love all your overlapping killers and clueless killers and can’t get enough of them!

  2. Posted July 31, 2006 at 9:25 pm | Permalink

    Hi Sandra,

    not sure why you are getting an ordinary killer. Look carefully – it’s a 12×12 puzzle, not 9×9.

    4 sub-puzzles overlap heavily so you may not have noticed that it’s a butterfly…

  3. Sandra
    Posted August 2, 2006 at 11:46 am | Permalink

    Thanks. With only half a brain how do I cope? With a large bag of erasers and lots of time!

  4. chris
    Posted August 7, 2006 at 2:48 pm | Permalink

    Hello, all I can see is a grid without numbers; am I missing something ?

  5. Posted August 15, 2006 at 11:57 pm | Permalink

    July 28 is definitely “hard”. After 6 hours of studying, I must not understand the clue on twin nonets, N8

  6. Posted August 25, 2006 at 12:20 am | Permalink

    ok, got July 28, as usual more than one way to skin the cat, and I was making it harder than it needed to be, aloha

  7. Terence Hainsworth
    Posted September 10, 2006 at 10:54 am | Permalink

    Loved the July 28th Butterfly Killer Sudoku. Hoping you will do another one soon.

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