Last change: 8 april 2018
There is a good website explaining all different kinds of overlapping Sudoku's:
http://sudopedia.enjoysudoku.com/Gattai.html
Below are very big Sudoku arrangements.
Source website http://www.rcbroughton.co.uk/sudoku/forum/viewtopic.php?f=4&t=13
All original created by Ruud van der Werf in 2006-2007
Shaolin X (25)
Up till now the SiSeSuSo Solver could NOT solve this Shaolin X 25 .
I first found this at http://forum.enjoysudoku.com/clueless-shaolin-x-t5099.html
What a beast:
25=4x4+3x3 connected X-Sudoku's and the 26th is a scattered X-Sudoku.
All overlapping parts are clueless! And the diagonals also contain all 1-9.
Too many cells are open and SiSeSuSo is not smart enough yet.
In version V3 of the Solver are implemented:
Naked/Hidden Pairs in diagonals and Box-diagonals elimination.
the clueless scattered 26th Sudoku is implemented in SiSeSuSo .
but still not resulting in finding a solution
After a day of bruteforce/backtracking I stopped the search for a solution.
DOAG (85) The SudokuSolver excel is here (V2 version)
SiSeSuSo can solve this Daddy of All Gattai #1 (November 11, 2007)
An arrangement of 85 Sudoku's in a 7x7 and 6x6 formation.
No X-Sudoku but the overlap areas are clueless .
4089 empty cells to fill.
Almost all can be done using basic eliminations and "box-to-rows/columns" or "pointing pairs".
No "Naked/Hidden Pairs" or "X-Wing/Swordfish" need to be used.
Only for the last 50 empty cells I have to use the brute-force searching part.
I don't know what elimination tactics are applicable here. Please let me know.
Some numbers on my Intel I5 :
4039 cells solved in 4:45 minutes:seconds and the remaining 50 cells in 40 seconds.
SiSeSuSo is not intended to be very speedy.
The "All Back" button to reset the arrangement to the original state needs 35 seconds eg.
On the rcbroughton forum you can find a second Gattai-85 Daddy of all Gattai #2,
which is completely solvable using only "box-to-rows/columns" or "pointing pairs".
Also included in the download as a second example-sheet.
MOAG (61)
On the rcbroughton forum you can find 2x "Mother of all Gattai" with size 61=6x6+5x5
Not tested/trying these yet.
Two pictures: https://m.imgur.com/wkHEJo1 and https://m.imgur.com/6HX7fqT
Generator?
Maybe I should build a generator for these kind of puzzles (after I solved the Clueless Shaolin X).
There are not so many big ones - at least I cannot find them :-)
I expect that making overlapping Sudoku's are more complicated than generating single Sudoku's...
On the other hand, solving this by hand, you must be a bit sick or having too much time to spend days on this.
They are generated by a computer, I expect, so what is the fun of solving them by another computer?