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#810, December 28 - January 3:
The Weekly Extreme Str8ts Puzzle

by Andrew Stuart
WARNING: This is the Weekly 'Extreme' Str8ts.
Only attempt this puzzle if you have time and patience.
Using the solver will not help you. (much).
Oct 18th 2024
The solver can now handle Str8ts variants. Yay! The solver button on the player will now pass an appropriate parameter.
Archive
Since there has been interesting strategy discussion on these puzzles and by popular request, I have opened an archive on the last thirty weeks. The discussion section is open for continued posting.
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Discussion...
Posts you have NOT read are in normal colors, older ones are in grey.
Please email me if you experience problems or bugs. Cheers, Andrew Stuart


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No full solutions please!

by: Cleo

 28-Dec-2025, 13:34
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40'after several errors. Like Thesoloist: 9 is not in column 2.
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by: hepa

 28-Dec-2025, 11:16
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3
 

by: OneGuess

 28-Dec-2025, 15:12
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 2 options where to put 8 in / diagonal - one option solves this one straight forward
 

by: web

 28-Dec-2025, 16:06
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1
That sounds really logical...
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by: acs
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2
 The Weekly Str8ts B puzzle #202
 

by: Cosmanita

29-Dec-2025, 07:59
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 Very nice one, standard B-Power.
 

by: optimator

 29-Dec-2025, 12:15
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 it took longer than it should have, but like Cosmanita
 

by: pax

 29-Dec-2025, 18:39
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WC, time enough over X-Mas ...
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by: acs
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3
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 The Weekly Str8ts puzzle #810
 

by: flowerwaffle

 28-Dec-2025, 12:39
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 Whew, chewed way too long on this one!

I'm interested in whether someone found a chainfree solution, as I cannot see any way forward without this pesky last chain:

x-wing 3 (AB89)
x-wing 2 (AB69)
UR: if AB8 contains 1, then AB689 has two solutions -> AB8=34
setti 3: col. 6 contains 3
chain(? might be considered VCE?): if GHJ3 contains 2, then: x-wing 2 (HJ13) -> 2 in J1234 and no 2 in GHJ4; this means that the solution to J4 simultanously must be <=5 and >5, contradiction. -> GHJ3=345
setti 7: E89=78
UR: if GHJ4=678, then AB4689 has two solutions -> GHJ4=123
chain: if 4 must be in every row/column (so H9=4) this eventually leads to a contradiction -> 4 is missing in one row/column, C5=6

(some steps might be optional, this is just the log of my first play through)
 

by: qk

 29-Dec-2025, 06:50
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 At acs: Thanks a lot for the puzzles!
At flowerwaffle: Although I'm not sure whether/where it helps, I used UR in HJ1234 such there could not be a 1 in H1234.
 

by: flowerwaffle

 29-Dec-2025, 16:01
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@UZ: Is the last chain what you're confused about?
setti rule makes 4 mandatory in 8 rows/columns, but we don't know if 4 could be mandatory in all rows/columns or not. So let's try one of the two possible options: If 4 would be mandatory in all 9 rows/columns, then H9=4 (and also C5=4, but this doesn't tell us much here), which eventually leads to a contradiction somewhere in the lower half (where exactly depends on the order of entry in this chain). Since this is not the solution to the puzzle, 4 must be mandatory in *exactly* 8 rows/columns, which means C5 can't be 4, leaving only the other possible candidate 6 as the solution for this cell (also H9 can't be 4, but here are two candidates left over).

@qk:
This would be a helpful step instead of my last chain, but I don't see how that's an UR at this point. What am I missing?
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by: acs
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4
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 The Weekly Str8ts BX puzzle #202
 

by: Cosmanita

 28-Dec-2025, 10:42
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 Very nice one, B and X Power. I used a short interaction to decide C1 using box 4.
 

by: optimator

 28-Dec-2025, 11:01
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 5' nothing tricky
 

by: WolfgangL

 28-Dec-2025, 14:32
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 Like optimator, standard tools only, thanks!
 

by: kmr

 28-Dec-2025, 18:25
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 Took me longer. Standard BX techniques but also VCE needed. Great fun, thanks.
 

by: ThomasF

 28-Dec-2025, 20:36
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Very nice, solves with BX-standard tools
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by: acs
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2
 The Weekly Str8ts X puzzle #202
 

by: OneGuess

 28-Dec-2025, 14:14
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 difficult - so again, guess needed - only one option left in center-X (2 others excluded with head chains) and one guess, where to put 3 in row J
 

by: pax

 29-Dec-2025, 05:48
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Very nice, no guess, HC's, setties 6, 2, 8 and the combination thereof...
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  • 28 min - nur mit tipps von flowerwaffle, danke!!
    - humpti dumpti
  • 23 min- really not easy, but i solved it :)
    - effchen
  • 15 min - chain in the end, settis before
    - Susan
  • 25:55 - Finally a good decision on D5 made my day.
    - Latimer
  • I stuck even with the hints of flowerwaffle (what means the last sentence?). With qk's hint I made a quick solution. Thanks to all!
    - UZ
  • 33 mins with hint and lucky guesses Thanks!
    - CC
  • ~60' I needed 2 chains
    - optimator
  • 2h, high/low in col 4, dann ebenfalls C5 richtig geraten. Schwer aber machbar. Danke Andrew.
    - S. Walt
  • 30 minutes with C5 guess. Lots of fun…
    - EddyBear
  • 31' after 3rd attemp and C5 hint. Thanks!
    - Jim
  • 21 min on second attempt, needed Andreas' hint - thanks. See you in 2026!
    - Beate
  • 26' with help. Thanks for all of you who provide advice, I enjoy this place here a lot.
    - l.
  • two chains had proved wrong. needed flowerwaffle's help. Merry christmas 2 all.
    - A B Traherne
  • 41 min - hi/low col4, setti 4 und 2, C5 richtig geraten
    - Rot
  • 19' secnd attempt, now with help.Danke flowerwaffle.Happy New Year to all, and espacially to Andrew - und Danke!
    - barbara
  • only with flowerwaffle's. second UR
    - Gerd
  • same procedure as jgrab independant of him :-) after col 4 hi/low setti 2 and 4 ca. 2 hour
    - b*k*
  • like some others some guessing needed
    - ThomasF
  • c5 - like andreas. Happy new year to this nice community
    - chris1
  • 57’ andrea’s hint helped
    - Richard
  • Very difficult. Help from flowerwaffle and Andreas needed, thanks!
    - MrL
  • 40 min; hint: 5 x no 9
    - Alfredo
  • >2h until I eventually just took the chain. Some fine URs though!
    - flowerwaffle
  • 47' - needed some chains and OR - thanks for 2025 str8ts!
    - COM
  • ...sorry,C5, not C6
    - Andreas
  • ich kanns gar nicht glauben, nach vielen versuchen doch noch gelöst. also mich hat eher die 9 in G weitergebracht.
    - dersoloist
  • Only two options on C6. Use the right one and you can solver this str8ts.
    - andreas
  • 1:10 - like jgrab
    - Hel
  • 45 min. settis, wings, nice
    - juehe
  • CE and column 3 give the answers... is there an 8 in column 3?
    - wal
  • 1:13:16 ziemlich schwer
    - zoo-pony (Tartlau)
  • 45min; needed a few chains
    - 7iron
  • Susi is right, I needed a HC though
    - easydoesit
  • 41 min; to avoid an UR in H89 and E89, H89 has to contain a 4 or a 5 which leads to H3 beeing a 3. After that the hole thing collapsed.
    - Snoopy
  • 51 min - find the right position of 1 in row H - the coolest str8ts since weeks!
    - Susi
  • Done WC, with a long HC on H4, 1h 8'
    - pax
  • 44 min; needed a hi/lo decision on col 4, then Settis and a HC. Good level of difficulty!
    - jgrab