I realized that I never posted a classic Butterfly Sudoku puzzle on the main page of the website. A few of them have been posted on the Daily Sudoku Variants page, but the puzzles posted there disappear from this website after a week.
So… to rectify this issue, I am presenting you with a
Butterfly Sudoku Overlapping Sudoku Variant Puzzle
There are 4 classic Sudokus inside this one. They overlap heavily. Each one of the four starts (or ends) in one of the corners. So… even though there are 12 cells in each row and column, first 9 belong to one sub-puzzle and last 9 belong to another one. Make sure you are clear with the rules, or ask me to clarify again.
How do you solve Butterfly Sudoku? Well, all classic Sudoku solving techniques can be used; in addition, Twin Nonets are basically a must for this layout.
If there is an interest in these, I might publish a sudoku book full of Butterfly puzzles 
Difficulty: THINKER
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The solution to Butterfly Sudoku.
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2 Comments
This one was a toughy, but we loved it. Publish some more like it.
Today I bought “Outside Sudoku and its Variants” book by you. Looks very good as of now.