My first generated arrangement of 13 overlapping Sudoku's. 5-may-2018
Symmetrical and of course all overlapping area's are clueless and also the 14th Sudoku is completely clueless.
This Sumo has 5 olympic rings (A), 3 medals (X) on 3 podia (W).
A=Asterisk, X=Sudoku-X, W=Windoku
2 Bands in the middle contain 7 consecutive empty boxes.
The center boxes of the 3x3 grids form the 14th clueless grid.
This 14th grid is a clover (A+W), light yellow in the picture.
The only technique required to solve this is: box to columns/rows/diagonals/... vv.
To download: The xls with V3 engine is here
In code:
Copy lines including first line and use PASTE button in SiSeSuSo