Logic Masters Deutschland e.V.

Friends in unknown lands (chaos construction)

(Eingestellt am 11. Juni 2022, 13:10 Uhr von filuta)

After some very small puzzles lately, finally one with a full sized grid, which I created already some months ago, but didn't dare to post it until now.

I would like to dedicate it to two amazing people I met through this hobby of ours, Kafkapharnaum and Piatato, who are coincidentally also people who spent a lot of time with this puzzle helping me test it (until Piatato was finally able to crack it).

It was an amazing journey to set this one and I only hope it will be for you to solve it too. And as always, I will be happy to read your comments.


-Standard irregular sudoku rules apply, the regions, however, must be deduced by the solver. Some region borders are given and must be respected.

-All regions are orthogonally connected and are numbered by distinct numbers 1-9. The number of the region corresponds to the digit in its upper left corner (the leftmost cell in the highest row).

-A cell is called friendly, if its digit matches the number of its row, column or region (or more of them simultaneously).

-A border between two regions is friendly, if at least one of its adjacent cells is friendly.

-The number in the upper left corner of the cage shows the sum of the digits in the friendly cells within the cage. Digits may not repeat within a cage.

-The clues outside the grid show the number of the friendly borders in the corresponding row or column.

penpa+ link (answer check on digits and edges)
f-puzzles link
ctc app link

Lösungscode: row 4 and row 9 (without a comma or a space)

Zuletzt geändert am 11. Juni 2022, 23:40 Uhr

Gelöst von Piatato, polar, JayForty, henrypijames, kolot, Steven R, Niverio, KNT, PrimeWeasel, fjam, Vebby, jkuo7, hepcecob, Prutsbeest
Komplette Liste


Zuletzt geändert am 21. Januar 2023, 10:44 Uhr

am 20. Januar 2023, 19:07 Uhr von Prutsbeest
This puzzle was brutal! It has cost me sweat and tears to solve this one! I am going to consider whether I should ever solve any more of your puzzles, Filuta, it's too time-consuming! ;-) thanks!
haha, thank you so much for your effort!

am 19. Oktober 2022, 17:44 Uhr von hepcecob
This was absolutely insane. By far the hardest puzzle I've solved. Who ever said "go out to the park to solve", you'll need to bring a tent and a week's worth of food and water. Absolute insanity.

No biofication needed, everything is pure logic... but damn, you gotta fight for every single clue, all the way to the very end.

am 7. Juli 2022, 15:14 Uhr von Vebby

Zuletzt geändert am 19. Juni 2022, 12:48 Uhr

am 19. Juni 2022, 00:07 Uhr von PrimeWeasel
Almost the hardest puzzle I ever solved! I thought about giving up, but I just couldn't do it. What a ride, thanks filuta!
Thanks, I'm happy to see you didn't find any alternative solution :)).

Zuletzt geändert am 22. Juni 2022, 06:46 Uhr

am 18. Juni 2022, 19:11 Uhr von Niverio
Do not try this at home. Go to a park or something, it will take a long time.
but jokes aside, it was impressive to see you and KNT solve it so (relatively) smoothly

Zuletzt geändert am 18. Juni 2022, 21:26 Uhr

am 18. Juni 2022, 19:11 Uhr von KNT
very easy puzzle
haha, 3 mins 45 was still an impressive time :))

Zuletzt geändert am 14. Juni 2022, 10:25 Uhr

am 14. Juni 2022, 10:07 Uhr von kolot
Crazy puzzle. THE hardest puzzle I have ever solved. I am happy to see my name in the list of solvers of this puzzle.
I'm happy to see your name on it too, congrats for an amazing solve!

Zuletzt geändert am 15. Juni 2022, 16:27 Uhr

am 14. Juni 2022, 07:42 Uhr von henrypijames
By my own metric, this puzzle has to be rated 7/5 for difficulty - four times as hard as a typical 5/5 (and twice as hard as a 6/5).

The difficulty is not just off the charts, but utterly relentless, never letting up for a single step. Really felt like squeezing water out of rocks - which, theoretically, is possible (just like - but also as fantastical as - this puzzle):

Thanks to @filuta for chatting with me throughout my 16+ hour solve over three days. Never needed so much handholding on a puzzle.
Thanks, it was actually quite something for me to see your progress almost in real time.

Zuletzt geändert am 14. Juni 2022, 03:33 Uhr

am 14. Juni 2022, 00:04 Uhr von JayForty
Extremely clever and tricky puzzle! Great fun exploring and trying to squeeze every tiny bit of logic out of the unusual ruleset. By each deduction it kept getting harder and harder, but still very satisfying. Thank you!
Thank you!

Zuletzt geändert am 13. Juni 2022, 17:35 Uhr

am 13. Juni 2022, 16:53 Uhr von polar
Absolute madness of a puzzle! The break in really draws you in and each deduction afterwards feels like an achievement in itself. My favourite puzzles are always the marathon ones that are impossible to put down and this certainly met that criteria :) Thank you!
Thank you and congrats for a great solve!

am 13. Juni 2022, 13:38 Uhr von kolot
Finally I got the break-in. I have got two digits now. Very happy with that. :-)

Zuletzt geändert am 12. Juni 2022, 18:54 Uhr

am 12. Juni 2022, 17:07 Uhr von PrimeWeasel
I've got the break-in in half an hour, very cool I must say, and exciting, now I'm moving on to actually solving it :)

~Haha, I'm not getting anywhere yet.

am 12. Juni 2022, 13:21 Uhr von kolot
@Piatato: Why would I be scared? Only one day passed since the puzzle is published. I have 3 months and 29 days for figuring out the break-in. There is nothing to be scared of. :-)

am 11. Juni 2022, 23:40 Uhr von filuta
corrected rules in the online solving links

am 11. Juni 2022, 22:58 Uhr von filuta
corrected rules

Zuletzt geändert am 11. Juni 2022, 23:02 Uhr

am 11. Juni 2022, 22:32 Uhr von henrypijames
Digits may repeat in a cage?
oh, thank you so much for noticing, completely missed that, just corrected the rules (they may not).

Zuletzt geändert am 11. Juni 2022, 23:50 Uhr

am 11. Juni 2022, 22:27 Uhr von Piatato
I really didn't mean to scare people off, btw, haha! I'll say that the break-in is unbelievably elegant! Please give this incredible puzzle a try, everyone!

Zuletzt geändert am 11. Juni 2022, 23:04 Uhr

am 11. Juni 2022, 17:25 Uhr von Kafkapharnaum
Piatato did it, the madlad! :D I still have the work I did on this one somehwere myself, so even though I'm not doing much puzzling these days, I'll certainly get back to it at some point -- I definitely did not forget about it; it's a lot of fun to work through, and as usual, mind-bendingly creative, or I should say even more than your usual unparalleled creativity in fact!
*Also I just saw you made it on CTC again, and a MARK movie-length no less, major congrats! :D
oh, thank you!

Zuletzt geändert am 11. Juni 2022, 14:40 Uhr

am 11. Juni 2022, 14:28 Uhr von marcmees
Q: does the numbering of the regions happen in reading order L to R downwards ... whatever Left top cell comes first, second etc ... - it would give one easy digit to start with - or at random, to be found by the solver?
No, there is not necessarily any relation between the position of a region and its number.

Zuletzt geändert am 2. Juli 2022, 18:27 Uhr

am 11. Juni 2022, 13:22 Uhr von Piatato
Thanks a lot for the dedication, and for such a fantastic puzzle! Although it took me more than four months to find the break-in, the break-in itself is not actually that hard. What followed was a wonderful way to spend 5+ hours. :-D Definitely one of the hardest puzzles that I have ever solved, but also very beautiful and rewarding throughout. Amazing construction!
Thank you!

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