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#690, March 21 - March 27, 2026:
The Weekly 'Unsolvable' Sudoku Puzzle

by Andrew Stuart

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).

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.
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Saturday 21-Mar-2026

... by: osiguy

I think if you exclude forcing chains you can open this up by just doing two bowmans bingo at first:

larsdoku "000040080008630900700500600076000300500000008001000460003005001007089200040010000" --exclude fc,fpc,fpce,fn --steps

Solving: 00004008000863090070...
──────────────────────────────────────────────────
# 1 R3C6=8 [crossHatch]
# 2 R5C7=1 [BowmanBingo]
# 3 R1C7=5 [BowmanBingo]
# Rest is L1/L2

Saturday 21-Mar-2026

... by: osiguy

Ok from the stall point with my analyzer larsdoku bd=S9B8n8n849h042d2r082g0s110806032d092t2k070n7w057o0h060v0wbg070643840t038584057s7w9lac1s2b9g087sb801d09w2g04069wc4c4032k38055u9m011f1v070u0809021a26b804842g013c6a9iae

I see a series of eliminations that leads to a placement that opens the board, i hope this is helpful! There is another series of eliminations before a second forcing chain.

════════════════════════════════════════════════════════════
DETAILED SOLVE LOG (10 rounds)
════════════════════════════════════════════════════════════
Round 1
XWing 4 eliminations
R1C2: 6 | R1C9: 6 | R9C8: 6 | R9C9: 6
X-Wing: 4 eliminations
Round 2
ALS_XZ 1 elimination
R9C1: 7
ALS-XZ: 1 eliminations
Round 3
KrakenFish 2 eliminations
R5C6: 2 | R5C8: 2
Kraken Fish: 2 eliminations
Round 4
ForcingChain R5C7 = 1✓
Notes before: 1 7 → placed 1
Forcing Chain: all branches from bivalue cell lead to 1@R5C7
Page created on 03-May-2011, last modified on 30-May-2024.
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