Same as Snail Sudoku, I developed/invented this puzzle for 4th WSC. As I remember correctly, I was inspired by Olga’s Areas puzzle. I remember the question I asked myself: “Why don’t all areas have the same amount of cells, and all digits are placed exactly once?” I used it first time for TLSCBWSC. After that for OAPC 5, and OAPC 10 (Best of OAPC, as a part of 18th WPC), 10th 24 HPC, TST 2009 (Turkish Sudoku Team Selection) etc. This puzzle was used in 6th WSC, again if I know correctly Zoltan Horvath made them. Also you can find some in Zoltan’s Sudoku blog, Studiogiochi – for more Giulia’s challenge, Andrey’s Christmas Contest, etc.
Quelle: The Puzzle Robot