Schrödinger's Fog: More Complex Than His Cat!

[@MrGrog90]

gdc here. Thanks so much for this feature. This puzzle took quite a long time to construct in order to present this crazy ruleset in a (hopefully) crisp way. Thanks for everyone involved in testing and especially to the S-cell expert ViKingPrime for the support during development.

[@chris5619]

Excellent setting! I agree with Viking Prime that this is one of my favorite zippers, FoW, and Schrödinger's sudokus I have played!

[@WimmekeVL]

My cat wasn't being helpful but at least I think I better understand the concept of shrodinger cells now. Thanks for setting this gdc.

[@flinty8121]

Congrats man. ❤

[@nathanmays7926]

Absolute brilliance.

[@danielszanto2955]

@@WimmekeVL I think the cat did help and not help at the same time.

[@patrickgass787]

This is ViKingPrime and I stand by every word of that - a most-deserved feature, this one. If you're about to watch the solve, don't shy away from the apparent complexity, this is absolutely an approachable puzzle and one you will relish exploring for yourself first.

[@chris5619]

I agree with your assessment of the puzzle being one of the best of each category, and also a lot more approachable than it seems. I never really got hung up anywhere and somehow solved in 47m. I was hesitant to even start it looking at the video length. But the logic flows very smoothly! Edit: after watching Simon's solve, I must say I made a big mistake in my solve. When I revealed the two 2-cell tops to the zipper in box 9, I did not consider the fact that there could be two zippers overlapping. I saw that the center had to be somewhere below r7c9, and therefore falsely assumed it had to be one 7-cell zipper and then proceeded from there. Simon, of course, immediately realized there could have been overlapping zippers and then proceeded until he had enough info to rule that out. Edit 2: I feel a little better about my mistake seeing that Simon also made a mistake which he only found because his broke the puzzle. And I am definitely glad that my mistake did not break the puzzle because I would not have wanted to go back and figure it out!

[@MatthewMcDonald0]

I started and solved this puzzle thanks to this comment! Thanks for the inspiration, sorry for one fewer views today Simon

[@Yttria]

Loved it. Very unique and approachable.

[@asbjrnfossmo1589]

@@MatthewMcDonald0 Oh, I watch the solve regardless, unless the one and only problem is the break-in and the vid is very short. It's like seeing a reaction video if I solved it, and if I didn't solve it... it is like a more awesome reaction video.

[@gregresnik1830]

Great puzzle.... missed the opportunity to have a schrodinger cell in the corner containing 3 and another digit thus making it both 3 in the corner and not 3 in the corner

[@SolarEquinox]

I love how the start of the puzzle subtly tells you that the two cells equal each other by being connected by an = sign

[@KeiFlox]

Always a treat when Simon breaks out the guitar :)

[@dolf370]

"...even in this ludicrous puzzle, we can't include minus digits on the other side of the zipper. Do not even think about it. Constructors out there, do not think about it. That is a horrible thought, that doesn't bear any further research or interest, believe me." From the deepest wells of the 9th circuit of puzzlers' inferno there is immediately heard a bone-shattering scream in unison from tormented setters' souls: "Challenge accepted". This puzzle was so clearly above my paygrade that I did not attempt to solve it, but man, it was really a fun solve to watch.

[@evanvdl1996]

This might just be my favorite sudoku of the year, I had a grin on my face the entire time. I can’t help but wonder where this can be taken next for zipper lines! Wonderfully done GDC!

[@David_K_Booth]

Yes - I thought that what gdc put in R3C8 was particularly funny.

[@mahuhude]

Zipperlein (pronounced rather Sipper Line) are little (-lein) itches and gouts; or in general little pains you acquire over time when aging.

[@praematura]

I honestly did not think I'd make it through this one on my own, but did succeed in 38:06! Amazing puzzle, many thanks to gdc for it!

[@FelipeMesquita]

Those references, starting at The Shire, ending on Mordor, with the Eye of Sauron, absolute gold!

[@Zardoz37]

Normally I wouldn't even attempt to solve puzzle like this - Schrödinger cells and zeroes? too hard for this bear of little brain - but I'm on holiday and it's raining, so I figured, why not? And to my great surprise and delight, after about two hours and a wrong turn or two, I did manage to get it out. The break-in is marvellous and witty and not even too difficult. Then I watched Simon's solve, and even he got tripped up by the tricksy Schrödinger cell logic (though in a different place to me) - very gratifying. Thanks for a great holiday puzzle, gdc!

[@LiquorStoreJon]

LOVE the Intro! And a Fog puzzle to boot! Happy Thursday to us all :D

[@sonalita_]

1:06:58 "Somehow it knows" Simon, I'm sure people have said this before but Sven's wonderful software allows the setter to embed the solution into the puzzle - this always seems to surprise you! A moment's thought tells you that this is absolutely necessary for Fog puzzles otherwise the software would not be able to clear the fog when a correct digit is entered.

[@MeriaDuck]

23:00 negative numbers in Sudoku 🤔... The horror 🤣 I'd love to see it, but given how stuck I get even on GAS puzzles I'll be watching this space for thst 😂

[@MeriaDuck]

One thought I have for that: make five count as zero, have the even digits count as positive and the digits 1 3 7 9 as negative and one could construct zero sum killer cages and such

[@bluji1250]

I have the oddest memory that I have at least seen the concept of negative values (a digit counting as negative for cage totals etc.) on some sudoku channel on KZbin! Negative numbers wouldn't be far from that... 😁

[@kgbgb3663]

@@bluji1250 I may be imagining it, but I think there was a yin-yang a while ago where values in one were positive and in the other were negative, but I can't remember what the values were being used for. Possibly cage totals.

[@sly1024]

Simon still doesn't remember that the software can check Schrodinger puzzles, even though this is the Nth time we see it working.😂 Still love you, Simon! Amazing content, every time!🎉

[@EricMill]

Are you sure it's checking it, or is it just checking every other digit in the puzzle and letting those go unchecked? That would be just as good, since having all non-S-cells proves what all the S-cells are.

[@qovro]

@@EricMill It checks that you put the correct single digit in normal cells, and that you don't put a single digit in an s-cell.

[@rohitraghunathan]

I love that the sudoku community has just taken one of Simon's catchphrases and turned it into a standard ruleset. Edit: Looking forward to someone making a puzzle with negative digits now

[@asbjrnfossmo1589]

Some obscure XV grid where all XV are given but no actual Xs or Vs in the grid? And it's empty except for a 3-cell bent killer cage adding to zero? No, I don't think anyone would want to set, solve or watch that ;)

[@orsonzedd]

I want to watch that @@asbjrnfossmo1589

[@elliotcondon]

10/10 👏. What a fantastic puzzle! One of my favourites of 2023. Thank you for the amazing setting

[@ADR014]

Take a drink every time Simon says Schrödinger…..☠️

[@AhsimNreiziev]

This puzzle led me to consider an interesting possibility, and that possibility led me to ponder an interesting question: if there was a Sudoku with Schrödinger cells, and the solution of that puzzle had a Schrödinger cell in one of the corners, and that Schrödinger cell had a 3 as one of its digits, would that Schrödinger cell get a song? Also, it's fairly easy to see how the solution checker can know that the solution is correct even though some cells (9 of them, to be precise) only have central-pencilmarks in them. It's the same way the software knows to clear fog cells when a correct digit is entered: the solution of the puzzle, including its Shrödinger cells, has been included with the puzzle for the software to check against.

[@stephenbeck7222]

I believe in the schrodinger puzzles, the solver checks for ‘blanks’ (no big digits) in the Schrödinger cells. It doesn’t look at pencil marks.

[@13vatra]

That's three and not three in the corner. That's three and not three in the spotlight both losing and not losing their religion.

[@RichSmith77]

​@@stephenbeck7222Yes. Easily confirmed by deleting the contents of the Schrödinger cells at the end. It still confirms you have the correct solution. If you have all the non-Schrödinger cells correct, it is a trivial exercise to fill in the Schrödinger cells with the missing digits, so it just assumes you will have those correct if everything else is correct.

[@Anne_Mahoney]

If there was a 3 in a Schrödinger cell in the corner, then Simon would be both singing and not singing.

[@MarkBennet10001]

At 22:15 - now everyone is thinking how to make a puzzle with negative modifiers ... and more vicious versions of such

[@omri.d]

What about negative numbers killer sudoku?

[@glum_hippo]

There have been quite a few puzzles with negative modifiers. I even have made one with zipper lines, but it’s really not noteworthy enough for this channel

[@PhilBoswell]

@@glum_hippo has anybody tried using the numbers between -4 and +4? It seems so obvious that I feel stupid asking, but some questions need asking ;-)

[@anaayoung9142]

This one was one of the best video on the channel. Sudoku: awesome fog puzzle with amazing zipper line Solve: super good as always, and you find your mistake pretty quickly Lord of the Rings: present. Super present. And I love it!!! Shire, Rivendell, Mordor and the Eye of Sauron!!!! Our little hobbits would be happy to be on this channel!! Thanks for the solve!!! 🤗

[@Rubrickety]

It's amazing that such a simple setup can make my brain hurt this much. 😅

[@MarcusTheDorkus]

This one certainly wasn't easy but easier than I expected and quite fun!

[@isaacthek]

This took me about 38 minutes tonight on the timer, but I worked it off and on for hours as I celebrated a friend's birthday. This was great fun!

[@hoseyniali]

22:53 Simon has to add this few second at the begining of every suduku solve with negetive number on it 😂.

[@Coyotek4]

36:34 ... can't get enough of that wonderful fog Nice puzzle!

[@chipsounder4633]

This is crazy clever.. loved the way you delt with the breakage in column 3. I was very impressed with that one ❤

[@simonwstrong]

22:49 Love how Simon cannot help himself dreaming up even more complex variations, then tries to put the genie back in the bottle by pleading with constructors not to create them !

[@davidrattner9]

Loved this solve from you Simon. Fog, plus a guitar intro, along with Lord Of The Rings references!! Just wonderfulness!!

[@johnpauladamovsky86]

I feel like the great "gdc" was chosen to function as a conduit for the eternal source of wisdom, when he channeled this puzzle down from the Crystal Blue Persuasion which transcends all that comes to exist.

[@rm6176]

ty for showing me new puzzles and reenergizing my love of sudokus. I Much Appreciate the creators and their time to make, it is my fun to do.

[@Samuraivillain]

My second puzzle before watching the video! 01:16:59 I did have to watch the explanation on the Schrodinger cells but once that made sense the puzzle worked out wonderfully

[@xerodeus2337]

the fact it only tripped you up once AND you managed to find the mistake was pretty cool

[@markp7262]

28:17 finish. An excellent puzzle, lots of math fun with fog of war added. Fun fun fun!

[@elekvault]

I figured the start quickly, but the "avoidance of doubt" part is not in the linked puzzle, and I was super confused as to how it worked and had to come to the video to see it.

[@jon-tabbypiper6554]

Brilliant. Absolutely love this puzzle!

[@rmjarvis]

Managed this in only 50 min. Always excited when I beat Simon's time. This was definitely a really fun puzzle! I loved the way the Schrodinger cells and 0s interact with the zippers. Made for some very interesting logical deductions.

[@FrancisFjordCupola]

I love how at 1:01:25 in Simon highlights the third column, saying "I haven't filled in 1589" when on the seventh row of the column the next numbers in the row are: 518 ... leaving a skyclad single 9. "I can sense this digit is under pressure," is simply golden. Sometimes I wonder if Simon is distracted too much by genius level math to spot what's right in front. Sometimes I hope he's just playing a game (well, duh, Sudoku one might hope) with us and leaving us room to feel smart. Never change! :)

[@kpwxx]

A helpful adjustment to the rules fir a beginner would be to clarify that the number the pairs of digits on a zipperline have to add to is the digit/sum of digits in the circled centre of the line. I'm not familiar with zipperlines and thought from the rules that they just have to sum to to the same unknown number.

[@jeremyneale8423]

Even as someone familiar with zipper line puzzles I interpreted "digits an equal distance from the circled centre of a lavender zipper line sum to the same number" to mean that the digits in the cell x distance from the centre in one direction is equal to the digits in the cell x distance from the centre in the other direction. I just assumed that it worked in a differently to the zipper line puzzles I'd already tried.

[@sarahsander785]

The name of this one is hillairous, it's such a great wordplay on Zipper Line and Zipperlein (German for "ache", but it's a dimunitive and usually used in a humorous way to refer to all the small body pains old age brings - or, more sarcastic, to poke fun at people who are constantly complaining about small aches to get attention).

[@jonathansperry7974]

75 minutes. But more importantly, I finally finished one without needing to watch for any extra bits of logic from Simon!

[@MorganZex]

This puzzle was truly amazing. It can look intimidating at first but it wasn't too hard to solve (this is actually the first and only puzzle with schrodinger cells that I've been able to solve on my own). What a late year treat!

[@Lucashallal]

48 minutes, fascinating ruleset

[@SamuelSandeen]

I find it so amusing that Simon said that negative digits on zippers didn't bear thinking about and then loved a puzzle with negative digits on zippers.

[@dangrene617]

Wowzers, probably the most challenging I've ever found a FoW puzzle. Took a full 40:11, and very nearly called it quits. What a satisfying achievement though! Brilliant puzzle.

[@coralfeatherstone7019]

I love Schrödinger sudoku, and this particular combination is awesome. Those zipper lines turning back on themselves are fun. It's my favourite puzzle in a long time; which says something considering the brilliance of some of the recent puzzles.

[@prototypesoup1685]

Schrodinger Sudoku is my absolute favorite variant! So much hilarious logic. Forces the solver to stop and think - especially slower people like me. When I reached that 13 pair in r4c4, I kept thinking "how do I resolve this?" lol

[@SupremeOverlord24]

I wonder if there is scope to have 0 digits in a sudoku without the Schrodinger's cells (ie 0-8) - seems they can make some unique logic with rules like zipper lines.

[@chocolateboy300]

I finished in 74 minutes. This was very fun, but Schrödinger's cells rulesets always mess with my scanning ability. I messed up on one part cause I thought it was pair rather than a collection of done cells. The break-in was very satisfying, putting in two 0s at the same time. Great Puzzle!

[@dinane]

This is one of my most favorite puzzles and solves on this channel. Thank you!

[@Stompound]

The breakin for this puzzle was super fun and interesting

[@lalalalalalalalal567]

Never knew schrodinger was also a verb until I started watching this channel

[@tobiasreckinger2212]

Even though I solved it without any help I can not comprehend the fact that it is solvable from only those two cells in the beginning. Have to admit I was very surprised when the 4 appeared.

[@brettduffin8412]

Haha, the LOTR references were spot on, in particular the eye of Sauron. Great.

[@Swisswavey]

32 minutes here. I love the Schroedinger puzzles, this was a great use of them

[@HalfBakedLunatic]

Excellent coverage of all the oddball rules. I was thinking that the only thing not included was a Schrödinger cell that had a zero in it ... and we did indeed get one in the end. Fabulous!

[@Annawastaken]

What a great puzzle&solve!

[@danielharmon1204]

I've never been this early to a CTC video. I'm gonna watch the video before I attempt it myself, I think.

[@Gonzalo_Garcia_]

17:37 for me. What a great puzzle!!

[@przemekmajewski1]

fabulous puzzle, it took mi around an hour, so it is close to 1 simon :D fantastic setting with all the "surprising" Schroedinger cells

[@levb258]

47:39, with a little bit of Simon's help for the break-in. What a lovely puzzle!

[@DarrenNakamura]

Finished in 98:51. I don't think I could have done it without the fog feedback telling me I had bad logic though. Several points I had what I thought would be a good digit and it wasn't, so I had to backtrack to see what was wrong, and it was always a Schrodinger cell I hadn't fully considered.

[@MrHullRockers]

Kayleigh intro, nice.

[@constanza1648]

i was a little scared when I see the length of the vid, but I give it a try, and it is not terrible difficult. I made a couple of mistakes here and there, but fog is really helpful to point out any mistake you are making.

[@etienneschramm83]

61mn for me. Really nice puzzle, nice logic from start to end. Thank you, gdq!

[@soulbound11]

Such a beautiful puzzle. Really enjoyable to solve and watch being solved. I only had one stumble as well, but mine was in box nine with that wily zipper in the shadows.

[@paula-zzz]

i love when simon plays the guitar for the intro :)

[@Yttria]

Absolutely loved the puzzle. Quite approachable with unique logic. (39:04 solve time for me)

[@philipmetcalfe4736]

Strewth!!..being a mere mortal....and love fog of war puzzels...and a few glasses of wine .I pssed this one bye....

[@omri.d]

I really loved the episode, and the puzzle! And also get to scream at the screen about the 7 at box 4🎉

[@michaelandersen-kk4fc]

yes he should have marked the schøderinger in box 7 way before that.

[@WimmekeVL]

Not sure if Simon will get to it, but where does 9 go in box 2 is where I went. But that didn't mean a 0 had to go on the other side of what appears after that. So I'm too dumb for this puzzle. Hopefully I won't feel as intelligency challenged after watching this video.

[@Qurqirish_Dragon]

37:54. Quite a fun puzzle. The biggest mistake I made was forgetting that 0+Shrodinger=X will work when the center of a zipper sees both summands - although that really helped at one point.

[@ryaneakins7269]

Hobbits in the Shire are an odd metaphor here :). You ask pretty much anyone to name a hobbit or two, and they'd probably only be able to name the ones that _didn't_ stay in the Shire :p. Still a very good puzzle, and an marvellous solve. I'm not a fan of Zipperleine, but there are some interesting interactions here as they overlap and bend back upon themselves.

[@inspiringsand123]

Let's Get Cracking: 08:05 Simon's time: 58m51s Puzzle Solved: 1:06:56 What about this video's Top Tier Simarkisms?! Bobbins: 1x (52:41) Knowledge Bomb: 1x (39:00) Three In the Corner: 1x (47:41) You Rotten Thing: 1x (1:06:30) And how about this video's Simarkisms?! Ah: 20x (09:42, 17:15, 28:16, 29:03, 29:25, 31:13, 32:57, 35:34, 43:42, 43:42, 45:18, 48:05, 48:49, 52:39, 53:53, 59:16, 1:00:27, 1:03:14, 1:05:02, 1:06:08) Hang On: 15x (08:18, 08:18, 28:16, 29:06, 32:35, 32:35, 37:07, 37:25, 38:07, 48:05, 49:07, 49:07, 49:07, 52:08) Beautiful: 9x (31:07, 36:29, 43:50, 43:53, 45:09, 45:11, 57:48, 1:07:17, 1:07:19) In Fact: 6x (02:53, 08:12, 14:04, 25:35, 44:49, 1:01:56) What on Earth: 5x (30:43, 34:48, 37:25, 1:00:27, 1:02:01) Sorry: 5x (21:53, 32:44, 54:02, 55:14, 1:00:58) Clever: 5x (29:25, 29:29, 31:16, 1:07:41, 1:07:44) Brilliant: 5x (12:59, 1:03:22, 1:03:25, 1:07:08, 1:07:08) Surely: 4x (33:29, 37:03, 40:44, 48:14) Obviously: 4x (01:29, 01:32, 18:16, 26:54) What Does This Mean?: 4x (21:15, 31:31, 56:00, 1:05:30) Pencil Mark/mark: 4x (15:42, 15:59, 31:46, 1:01:34) By Sudoku: 3x (46:14, 1:04:43, 1:05:35) Bonkers: 3x (15:35, 29:58, 30:02) Bother: 2x (53:01, 58:31) The Answer is: 2x (29:42, 1:04:30) I Have no Clue: 2x (31:36, 31:41) Lovely: 2x (37:35, 1:07:29) Going Mad: 2x (1:01:16, 1:03:01) Wow: 2x (39:49, 56:24) Cake!: 2x (04:23, 04:24) Weird: 2x (59:09, 59:09) Good Grief: 1x (38:39) Nonsense: 1x (44:56) Naughty: 1x (49:35) Break the Puzzle: 1x (1:00:12) Incredible: 1x (01:05) Ridiculous: 1x (31:16) Gorgeous: 1x (32:57) Shouting: 1x (04:45) Intriguing: 1x (02:26) Most popular number(>9), digit and colour this video: Twelve (15 mentions) One, Two (86 mentions) Green, Blue (4 mentions) Antithesis Battles: High (2) - Low (2) Even (10) - Odd (1) Higher (5) - Lower (0) Highest (3) - Lowest (0) Outside (2) - Inside (0) Column (27) - Row (11) FAQ: Q1: You missed something! A1: That could very well be the case! Human speech can be hard to understand for computers like me! Point out the ones that I missed and maybe I'll learn! Q2: Can you do this for another channel? A2: I've been thinking about that and wrote some code to make that possible. Let me know which channel you think would be a good fit!

[@G4M1L]

Zipperlein is a German expression (maybe borrowed, not sure about that) meaning aches/minor pains Like in "Ihn plagt das Zipperlein" = "He is plagued by something" (roughly). Nice play on words here.

[@dalecooke944]

Loved the eye of Sauron

[@pranavsetpal]

I absolutely loved this puzzle!! gdc strikes again with a banger

[@danielauto3767]

Great idea for a new construction at 22:50

[@WeTheMajority]

Excellent guitar intro 🎉🎉🎉 cheers

[@BakingFiend-rl7mo]

Live me some fog of war. Can't wait to watch!

[@zaclewis1869]

That was a fun puzzle. I'd never done a Schrodinger's sudoku before, but even still I managed to get through this one. I liked the logic of it. I did get hung up on the big zipper line in box 9 though when placing a '9' in r7c9 didn't clear fog. Haha. I thought for sure I messed something up and went on a bit of a wild goose chase trying to find my mistake. It took me longer than it should have to realize it just meant that had to be the '7-2' Schrodinger cell. In fairness, I didn't use that unearned knowledge to solve the puzzle. I waited until I could logic which was which, which wasn't until near the end for me.

[@10prozenthimmel]

Zipperlein is a very old-fashioned German word. It describes minor ailments of elderly people in a tongue-in-cheek way, or can be used as an (even more old-fashioned) term for gout. I’m not aware if Schrödingee himself suffered from gout or lived to be old…?

[@kgbgb3663]

I think there was an easier way to see that those lines towards the end had to join up rather than run beside each other as you feared; there is no need to look at actual numbers. If that had happened, the centre of each line would have been a non-central cell on the other. A non-central cell has to be less than or equal to the central cell of its line, and only equal if the corresponding cell on the other side is zero. As each of the two centres has to be less than or equal to the other they must actually be equal. Hence there would be a zero on each line, but in different places in the box, thus breaking sudoku. Alternatively you could argue that the two centres have to have equal values so one of them must be schrodinger, and in this particular case both of the positions where the centres would have to be had already been shown to be non-schrodinger by the placement of schrodinger cells in other boxes. Edit: No, the first method I suggested fails. One of the zeros is just over the boundary of the box. But I think the alternative method still works, at least if you do things in the order that I did.

[@kgbgb3663]

CORRECTION For some reason I'm not managing to edit this comment -- the edit just disappears into the void. I just wanted to say that my first suggested method fails, as one of the zeros is just outside the box. But I think the alternative method still works, at least if you work in the order that I did.

[@ericpraline1302]

Enjoyable puzzle, thanks. For some reason I decided to make life more difficult for myself by thinking the puzzle had doublers rather than S cells, and kept having to shake off that delusion.

[@Tepalus]

"Zipperlein" is the german cuteification word for a small Zipper. "Es ist ein kleines Zipperlein" means "It's a small tiny Zipper". Idk if there is something similar in english.😅

[@michelle1427]

I took me some time but I actually did remember what the intro song was. 😊 (Marillion's Kayleigh)

[@cloudbringer104]

I had to listen to the intro twice to get it. I went to see Steve Hackett in the Usher Hall. Fish was in the audience and was signing autographs during the interval.

[@margaritashcheglova8670]

one way of doing the "negative (number) constraint" is to say in the rules that there are cells which deduct the number instead of adding it within other rules (like here where you have to add up numbers on the line)

[@harjutapa]

22:50 y'all heard Simon, we need a puzzle with negative numbers involved!

[@RoselynTate]

Absolutely loved this puzzle -- and my final time was 33:33, which just seemed too perfect not to share 🥰

[@Tesseren]

Every time I open the puzzle in the Android version of Sven's Sudokupad, it reveals different extra cells. First it was R2C2 (plus R3C4 and R3C5), the next time it was R1C1 (plus R3C4 and R3C5). Schrödinger indeed!

[@Darkstar2342]

btw, "Zipperlein" in German is vernacular for age-related ailments (originally gout, but all kinds of ailments can be called "Zipperlein"). It is rather uncommon these days, it's an old saying (my grandma and mom used it, it's been oder 20 years that I heard someone use it)

[@DOSSTONED]

Wow, the Schrodinger/sum rule made the deduction quite a different. More like sufficient condition vs necessary condition to me. For a normal sudoku, if the number 2 appear in a cell, you can just write it. For this s-sudoku, you can only leave it as a candidate.(it might sum to others) But the reverse situation kept: if the cell only contain number 2 as candidate, you can just write it as other numbers cannot be in the cell. So the other variant might be a new set of rules: some cells can be blank, you have to put 1-8 in each line/row/box and left exact one blank cell(left as X or some blockage). In these rules, you can write a digit if candidate only fit in one box(even other candidate can be in this box) but you cannot write number if cell has one single candidate(might blank)

[@piarittersporn]

Very exciting puzzle.

[@srwapo]

44:47, and I totally had to take a look to see how to begin. Zeroes make it hard! I had a hard time keeping track of doubles vs pencil marks.

[@markbrianbaker]

Nice puzzle gdc! I got stuck for a bit interpreting the U-turn in R3C3 as the line entering that cell twice, but once I understood it correctly, everything proceeded swimmingly.

[@yagamilight08]

Took me a fat hour n a half but it was a smooth flowing puzzle once u get past the initial stage

[@frankjiang1857]

Finished in 27:54. Not sure if I made an assumption that I shouldn't have? It seemed relatively straightforward to go through the puzzle. Fun puzzle!

[@iambicpentakill]

Hah! I called that not marking box seven's possible S-cells would come back to bite Simon. (I myself was unable to finish the puzzle)

[@icepyrox]

The whole time Simon is working on the lines in b9 I'm sitting here thinking "you have all the natural numbers penciled so you know what those 3 boxes contain even knowing one is Scheoedinger"

[@HunterJE]

39:58 "It's not 45, 36, or 18..." It's as quickly eliminated but in this puzzle did leave out one option there...