Logic Masters Deutschland e.V.

Opus Vermiculatum

(Eingestellt am 10. August 2022, 05:09 Uhr von KNT)

I am very excited to post this one. I've had this idea for a while now, but I think I spent more time thinking about this theoretically than I did actually setting it. Also apologies in advance for the extraordinarily long ruleset. The gist of this puzzle is that there are four 6x6 pencil puzzle hybrids to solve: a cave, a nurikabe, a snake, and a yin yang, but which grid is which puzzle is something for you to discern. There is also a linked nature of the grids regarding shading, which can be found in italics at the bottom of the rules. The ruleset for this puzzle is too long to put in a solving link, so you will have to refer to this page for the specific details of each puzzle type. Apologies again!


Within the grid you find four 6x6 sudoku grids. Each grid obeys has a different pencil-puzzle hybrid ruleset, but normal sudoku rules apply to all four grids.

Grid 1: Killer Cave

Shade some cells such that all unshaded cells are connected and all shaded cells are orthogonally connected to an edge. A cell with a number in its top-left corner indicates the sum of all cells "seen" within the cave in all four orthogonal directions. A cell with a circle in it indicates the number of cells "seen" within the cave in all four orthogonal directions, including itself. Digits may not repeat in the field of vision of any type of clued cell.

Grid 2: Yin Yang

Shade some cells such that all shaded cells are orthogonally connected, and all unshaded cells are orthogonally connected. No 2x2 block may be fully shaded or fully unshaded. A cell with a number in its top-left corner indicates the sum of shaded cells in EITHER its row or its column. A cell with a circle in it indicates the number of shaded cells in the 3x3 area centered at that cell.

Grid 3: Nurikabe

Shade some cells such that all unshaded cells are orthogonally connected and no 2x2 area is all unshaded. Shaded cells form islands, and on an island digits may not repeat. A cell with a number in its top-left corner indicates the sum of the cells on that island. A cell with a circle in it indicates the number of cells on that island. (Note this is opposite to "standard" nurikabe, where the islands are typically unshaded)

Grid 4: Snake

Shade some cells such that all shaded cells are connected, and form a 1-cell wide path that does not branch or touch itself orthogonally. The path may touch itself diagonally. A cell with a number in its top-left corner indicates that cell is unshaded, and is the sum of the digits of that orthgonally connected group of unshaded cells. Digits MAY repeat within these groups. A cell with a circle in it indicates the number of snake cells in the 3x3 area centered at that cell.

But, which grid has which ruleset is to be determined by the solver! However, we have some additional information to help us out in determining which is which: cells on either side of a border between grids have the same shading. For example, if R1C6 of the top left grid is shaded, then R1C1 of the top right grid must be shaded as well. Similarly if R6C3 of the top left grid is unshaded, then R1C3 of the bottom left grid must also be unshaded.

Good luck, and have fun! I expect ruleset clarifications to be needed, so I will try my best to respond to any questions ASAP. Furthermore, I have listed this puzzle as a 5 star for difficulty entirely because the ruleset takes some consideration to appreciate, but none of the individual deductions should be remotely near 5 stars for difficulty (at least, according to the judgement of the three people that tested this).

CTC app link

Penpa+ link

Lösungscode: The shaded cells in Row 4 of all four grids. First top left grid, then top right, then bottom left, then bottom right

Zuletzt geändert am 12. August 2022, 05:51 Uhr

Gelöst von tesseralis, PixelPlucker, Niverio, Vebby, the_cogito, DVFrank, polar, explodingsnail, zwooz19, filuta, harrison, Koalagator2, thoughtbyte, tinounou, ancarro, Agent, Jesper, MagnusJosefsson, Martijn314, Christounet, Jaych, cdwg2000, OGRussHood, kjholt, ascension, jkuo7, 85392, ONeill, Xendari
Komplette Liste


am 26. Dezember 2022, 18:05 Uhr von ONeill
Such a fun puzzle!

am 28. August 2022, 02:06 Uhr von Christounet
Magnificent !!!
The ruleset is indeed a beast in itself, and a lot to keep in mind along the way. But, coming from a great setter as yourself, I knew it was worth the effort and I’d be rewarded ! Loved the idea of matching the shading between the borders of the grids. And all the little details of the ruleset (May, May not...) that come into play at some point.
Thanks ++ again !!

am 26. August 2022, 08:42 Uhr von MagnusJosefsson
Wonderful! What a great idea, and very well executed. Most enjoyable throughout!

am 19. August 2022, 17:53 Uhr von Jesper
Very cool combination. Enjoyed it a lot, thanks!

am 18. August 2022, 05:26 Uhr von Agent
It was hard to believe that each grid solves uniquely once the inner edges are fully shaded.

am 13. August 2022, 04:50 Uhr von thoughtbyte
What a journey - a difficult, beautiful, very rewarding journey. One of the most satisfying solves in awhile. Thanks KNT!

am 12. August 2022, 05:51 Uhr von KNT
Made Killer Cave rules more clear, and fixed a typo.

am 12. August 2022, 02:03 Uhr von filuta
This is really the ultimate ambiguity idea. I also really liked some unique deductions in the grids on the left hand side.

just one note, even though I understand that the rules are too long for penpa/ctc app to handle, at least some kind of cheat sheet especially what the corner numbers/circles mean in different rulesets would be very useful if included.

Zuletzt geändert am 12. August 2022, 19:03 Uhr

am 12. August 2022, 00:29 Uhr von Elliptical
In the killer cave rule set, what exactly is the difference between "orthogonal directions" and "orthogonal connections"?

am 10. August 2022, 23:41 Uhr von explodingsnail
I got so stuck bc of very silly assumptions I made such as "You can only get the sum of 15 with the cells 12345", forgetting that the unshaded snake sums could have repeated digits and that you could have 2x2 unshaded areas in the killer cave solution LOL. I have a bad memory as well due to my ADHD, so the amount of rules caused me to lose track of them often (which is a problem with me, not the setter <3). When I finally moved past those things, the puzzle was really quite intuitive. Great puzzle, great idea!

am 10. August 2022, 14:00 Uhr von DVFrank
Wow, that was quite the journey! I spent a lot of time not knowing where to even begin, but once I figured it out, it was just a a lot of fun seeing the whole grid come to life! Thanks for setting this, KNT :^)

am 10. August 2022, 13:00 Uhr von Vebby
Lovely concept! Working out the shading was a lot of fun!

Point of clarification for the benefit of future solvers: All clued cells in killer cave are unshaded and all clued cells in nurikabe are shaded. Circles in snake and all clues in yin yang could be either shaded or unshaded.

Zuletzt geändert am 10. August 2022, 12:19 Uhr

am 10. August 2022, 12:14 Uhr von DVFrank
I have two questions:

For the Killer cave: Does a cell "see" itself? If it is shaded, does it see anything? (Equivalently, is every clue necessarily unshaded?)

And for the Nurikabe: Are clued cells necessarily shaded?


Hi DVFrank, the killer cave clue sees itself, and nurikabe clues are indeed necessarily shaded.


Oh that was quick! Thanks for the clarification! :^)

Thank goodness for email notifications for comments!

am 10. August 2022, 05:55 Uhr von tesseralis
It's a lot to take in at first, but once I grokked it, this had fantastic and fresh logic for all parts of it: disambiguating the puzzles, the edge logic, and the individual puzzles themselves! I would love for there to be more puzzles like this

Bewertung:100 %
Gelöst:29 mal
Beobachtet:3 mal

Lösung abgeben