#712, August 22 - August 28, 2026:
The Weekly 'Unsolvable' Sudoku Puzzle
by Richard Kröger, guest compiler
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WARNING: This is the Weekly 'Unsolvable' Sudoku, rated above 'Extreme'.
This is currently unsolvable by my solver, except perhaps with trial and error strategies.
Using the solver will not help you. (much).
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Changes March 2026
Due to the introduction of
Forcing Nets many Weekly Unsolvable puzzles can now
be solved. I have flagged all the Sudoku ones which are solvable. I am struggling to make any new ones so we'll
have to see if the Weekly can continue. The point of the Weekly was to provoke discussion and new ideas, so
that is progress. But my solution is unlikely to be optimal so alternatives are welcome.
Archive
Each week a new 'unsolvable' will be published and the previous will be accessible here from this archive section.
If you like very tough puzzles, these are for you.
Share and Enjoy
Supporter Members have access to all these puzzles going back to number 1.
Discussion...
Post an idea here...
... by: Norman Powell
Solved by Forcing Networks:
Forcing Networks - 1st Pass: 4B4, 9B6, 5D3, 2E8, 5G7, 9H4, 5J7.
Confined to Box, 5 is confined to Column 7 and Box 6.
Forcing Networks - 2nd Pass: 2C5, 2D3, 2D7, E7
Forcing Networks - 3rd Pass: 5A2, 2B8, 3B8, 3C4, 4D9, 7E7, 4F1, 4F6, 7F7, 4F6, 7F9, 9F9, 9G7
Solved F9=4
Forcing Networks - 4th Pass: 10 Suggested eliminations before finding Solution.
... by: Frans Goosens
#712
Combination 2-digits cells
F5=1 No solution, Undo calculation
F5=7 No solution, Undo calculation
G8=5 No solution, Undo calculation
G8=8 Wrong, Undo calculation
G8=5 No solution, Fixed
F5=1 No solution, Undo calculation
F5=7 Wrong, Undo calculation
F5=1 No solution, Fixed
G1=3 No solution, Undo calculation
G1=8 Wrong, Undo calculation
G1=3 No solution, Fixed
B1=2 Wrong, Undo calculation
B1=4 No solution, Fixed
B2=1 Wrong, Undo calculation
B2=9 ( H5=2 ) Solved,
Total solving time is : 152 sec.
Number of logical steps is : 18247
... by: Serban
# 712 G3=1 H2=6 J8=4 Basics to 25
1. B7=1 & D2=5 solve
2. B4=6 & F3=9 solve
3. B8=7 & C8=3 solve
