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#726, May 19 - May 25:
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).

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.
Share and Enjoy
Puzzles 1 to 250 are available as Puzzle Packs, just $5.49. Pack 3, 4 and 5 just released!

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: hone

For this summer’s oversized challenge a B-Puzzle is provided. As B-Puzzles can only have square numbers as grid length, the only option is a 16x16 grid with 16 boxes of dimension 4x4.
A 14x14 standard puzzle with the symbol of asteroid (38083) Rhadamanthus is also available.

Puzzles and solutions are stored as images in the forum. Puzzles posts also include a CSV format (0=Black, negative=Black cell clue). Links:

Update to my contributions archive in the forum coming soon. Easy access via


by: Ben

Add to this thread
A big thank you hone. I've already started Rhadamanthus (got to 9 solved so far)

Technically, you could quite easily have a 12x12 B puzzle, with 4x3 blocks, but I'm not complaining about getting a 16x16 block puzzle

by: hp

very nice difficulty level, nice pattern
shortest path for me beside CE:

3 fish 4, Setti 4, GAP, xwing 7, then the UR mentioned by Klaus GH23 followed by Setti 8


by: TheNewNormalOne

Happy Pentecoste, puzzlers.
I understand URs but can‘t apply them in real life. But UR followed by Setti 8 told me what to do. Thanks. Getting closer to understanding and HGI (human general intelligence)


by: BP

Add to this thread
Hi TheNewNormalOne! Could you explain why you find it difficult to apply URs? Maybe I or someone else can give you (and thereby others) some pointers.

by: kst



by: Hel

36' WC fun, thanks!


by: Martinus

Needs very good looks, CE and settis. Thanks a lot, kst.


by: kmr

Wonderful challenge. Needs B-Settis and VCE. Thanks!


by: optimator

took 2 tries. Thanks kst!


by: tg

Add to this thread
Wonderful. Chainfree. Thanks!

by: kst



by: kmr

Pretty tough. Needed a long HC to decide D9. Thanks, kst, for a tricky puzzle.


by: pax

Agreed, very tough. Needed a long HC to find an UR...


by: BP

A very short HC (or even SI) sufficed.
My crucial steps :

After 31 solved cells: B setti: 1,2 in Box 4 => 2 in E.

Later: 8 not in E or G. Both choices lead via CE in Box 4 or Box 7 to H1<>2.

Many thanks for the hard nut!


by: Tati

It's not so tough if you look at DEF123. My path to the solution was: In that box, either 8 or 9 must be missing. So if you put a 9 in row D, you have both those numbers in that box, so that can't be true. After that, everything falls into place.


by: optimator

after about 34 cells, I needed a chain on H8.


by: kris

As Tati showed (surely he meant row E, not D): It's all about box setti, besides CE. No chain/SI needed at all.


by: Tati

Add to this thread
@ kris: You're right, of course I meant row E!

by: kst



by: kris

Very tricky one, but I liked it very much, thanks kst!
My key steps were:
- multiple VCE in the middle X
- wrong choice for hi/lo in the upper left corner leads to sudden conflict in /-diagonal
- wrong choice for F4 leads to a quick conflict on C-F4


by: Cosmanita

I liked it very much as well. As Kris said, key is middle X, meaning checking consequences of both options in E5 for D1, D4 and E4. I used as well consequences of A1 for / diagonal.


by: optimator

very difficult for me, I made the same mistake twice. Many wings to finish.


by: Setti

Add to this thread
Very nice one checking the middle X options. Thanks for the puzzles.

by: kst



by: AndreasM

Thank you for this really interesting puzzle. Solvable at standard level (setti and VCE), but not as easy as one might think as first glance.


by: tg

Needed a chain...


by: Harm

The key for me was to find the position of 5 in Row J. J9 cańt be 5, otherwise UR in GJ1. So J1 =5. Similar argument excludes 3 from H7.


by: kris

@AndreasM: Are you sure?
I found 6-fish on 5, starfish on 6, 10-cell-UR leading to 8 on E2 or E3, however got stuck at 12 solved cells ... would appreciate some hint


by: kris

OK I see now, missed Harm's hint before


by: charliepat

With Harm's hint quite enjoyable. Many thanks Harm!


by: kmr

Incredible how it collapses with Harm's hint. Thanks to kst for a great puzzle.


by: Auwei

Add to this thread
@Harm: I saw the 2wing5 in cols 1 and 9, but not the consequences that lead to the solution via UR. Great!

by: Lurchi

Guten Morgen Klaus,
was ist ein "UR argument"


by: Klaus

Hi Lurchi (Salamander!?),

no offense, but...

this is an international forum. So i think its a matter of politeness and respect to write in english, if somehow possible (which i just assume now).

secondly i was raised in the spirit that you should not ask other people for an information you could easily get myself. if you google Str8ts UR, you will find stuff.

ride on


by: Jens

UR - unique rectangular
Klaus indirectly pointed out: GH23 shouldn't be only candidates 78, which wouldn't bring only one solution.
After a few wings and small fishes I used that hint from Klaus to got a single solution.
Thanks to Andrew and Klaus!


by: neunmalneun

En ce qui concerne la première partie de ton post, je ne suis pas tout à fait convaincu. Je pense que chacun devrait écrire dans la langue dans laquelle il s'exprime le mieux. Si cela vous intéresse, allez sur DeepL, les autres passeront simplement outre le post.

(traduit par DeepL)


by: kris

I fully agree with Klaus.
One could use DeepL himself to translate his post in english, instead of forcing thousands of other users to translate it.


by: Flo

Let's deal with each other peacefully, in whatever language. Especially now, when millions of people are celebrating Pentecost, the festival of reconciliation and community, of peace.
Wish you all a wonderful weekend
translated with deepl


by: Auwei

Just the right day for this discussion!
At Pentecost the apostles are said to have suddenly been able to speak new languages and spread the word of God in them.
I would ignore any contribution in greek, may it be good or bad.


by: Axel

Add to this thread
Sfortunatamente neanch'io parlo l'inglese ...
(senza deepl)

by: Klaus


nice UR argument bottom left makes it quite easy


by: hoke

Add to this thread
This beast is not a simple UR, that you see immediately. Instead it is a combination of big gap and UR, which I did not recognise until all other progress got to the end. I'm glad to have not read the comments before. Great puzzle, thanks Andrew!

Page created on 27-June-2010.
This page was last modified on 08-Jan-2023.
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  • 3hours
    - Julioflor
  • 45' (with breaks). Nice one, thanks!!
    - triemers
  • 38 min
    - relijo
  • Very nice level of difficulty. Just had to keep plugging away at settis, URs and fishes.
    - puzzled
  • 39' with some breaks, the UR does it
    - ThomasF
  • Nice, the UR is amazingly powerful
    - Jan
  • a nice puzzle for a sonny holiday. 45 min
    - ppoblid
  • 38 min, mit glück und erfahrung.
    - dersoloist
  • 36‘ never understand URs. But the UR here definitely helps
    - TheNewNormalOne
  • Not easy for me. Try an error in line D. more than 2h, nice puzzle for pentecoste. Thanks.
    - S. Walt
  • 11 min
    - Nessi
  • 36', 2. Anlauf, mittelschwer
    - zoo-pony
  • 12 min in second attempt. After getting stucked in the morning...
    - Susi
  • 27 min. - 2nd try; mainly wings
    - Nessie
  • At last one that was a little easier than the past few weeks!
    - essie
  • 24 min im 2. Versuch, UR GH23 war die richtige Spur
    - Rot
  • 34' on 2nd try, nice one
    - Richard
  • First time tried WC, but couldn't keep track of it all. Second try, 17'
    - Maven
  • > 1 hour - quite hard
    - selecti
  • 33 min, second attempt, just a little bit slower than Emma and tbr. Happy Pentecost!
    - Beate
  • I didn´t see the UR bottom left. Thanks for the hint, Klaus. Must have hat tomates on the eyes. So it lastet a little longer.
    - E.H.
  • ~30': swordfish, many wings, either G4 sets FJ3, and a setti
    - optimator
  • below 20 min
    - Loser
  • 17 min. strange, was totally stuck on first try, started again, a bit of settis and wingsand everything fell in place.
    - juehe
  • not tpo difficult, Setti 2 after the UR.
    - jgrab
  • 32 min but I needed a second try
    - Emma
  • 51' - needed some time to understand Klaus hint
    - COM
  • 32 min. - needed a 2nd try
    - tbr
  • 17min, yes, silke, this was fun
    - fred
  • 30 min, with the ideas of Klaus and Thorsten&Irina
    - Cosmanita
  • 37 min, wings, settis und UR
    - Torsten&Irina
  • 19 min, settis
    - humpti dumpti
  • Loads of settis and fun, thanks :)
    - Silke
  • 23min fairly easy!
    - susu
  • Done WC, but slow (50')
    - pax
  • 28' Was a little slow tonight. Settis rule the game. Not that difficult 4*
    - Manfred