A Sudoku With No Visible Cells (!)

[@Bonehead777]

Haha. I loved how Simon missed the floating 6 under his cursor at44 minutes in which would solve his 5/6 dilemma on same row. Not that I have ever done such a thing. 😗

[@toddbiesel4288]

When Simon asked, "What am I missing here?", I literally laughed like Muttley.

[@madusan1]

Simon is brilliant at solving but he is not the best at scanning (which he admits to). Obvious clues can often escape him, leaving me to scream into my iPad. "Simon, it's right in front of you! Simon!!!". Lol. Still love Simon's solves. No question he does have a very good solving mind.

[@kiphansen8319]

I think Simon's subconscious was trying to tell him something by lining up the cursor at that point. His conscious mind was having none of it.😅

[@andraques]

Simon is just trolling us lol

[@mongmanmarkyt2897]

@@kiphansen8319 absolutely none of it. But it's also great to see him get the answer in other ways too, to further prove an obvious number

[@paulinnanjing]

I'm always amazed at Simon's complete inability to do sudoku, in between his utter genius.

[@sacredsock8031]

44:44 Simon, what you are missing is the (second) most important rule in sudoku, look at where the cursor is

[@bobblebardsley]

That's a very pleasing timestamp.

[@monkeyunit4533]

You'd almost suspect him doing it on purpose.

[@wilburtron]

He's definitely trolling us lol

[@ronbalut592]

Only 5 minutes to see it.

[@Hakucho64]

@@ronbalut592 he gave us a good scare at 47:42

[@six_5000]

😂 please Simon, never change 😂 **Pencil marks 56 with a 6 in the row “And that’s all very well but it doesn’t do it does it?” **Places cursor over the obvious 6 “What is it that I’m missing here?”

[@tonyawright6020]

This! I was laughing so much.

[@brandonbernardo4410]

I was screaming at my screen lol

[@StephanSpelde]

That was hilarious!

[@russhellmy]

Came here to write EXACTLY this. 😂😅😂

[@JackofNoTrade73]

@@six_5000 Simon's having a laugh at us.

[@HunterJE]

49:28 "How long have I had this 6 for?" Since before you put the 56 pencil mark in and then immediately lamented not getting a digit while your cursor was hovering over the 6 XD

[@jaydyer3999]

Thanks for the feature! This ruleset has also been referred to as "house numbering", after the first puzzle I used it in, and I couldn't resist turning it into a fog of war after seeing the puzzle from FD and MaFC. Another way you can think about the opening is that the 1 in row 1 is going to be marked, as is the 1 in column 1, so those have to be the same cell.

[@markbennet9058]

Clean logic, as expected.

[@danielszanto2955]

That seems so obvious with the concurrent 1 in r1 and c1, I got it in 20 seconds. The indexing part and finding the marked cells was quick and easy, though after that came sudokuland where I suck so another 45 minutes... Anyway, that opening was really nice, you deserve a bow for it alone :)

[@BremSterPuzzles]

Stunning puzzle. Beautifully set.

[@longwaytotipperary]

What a fantastic rule set!!!

[@trisha2584]

Great puzzle. I got the opener in box 1 quickly but then I slowed down.....

[@18lolable]

44:16 So not only does he completely miss the 6 in r7c7 pointing at r7c3, he also then nicely places his mouse cursor over it seconds later for some world class irony.

[@michaelandersen-kk4fc]

yes I screamed about that

[@asadickens9353]

I saw the same thing! Simon is thinking on a different plane! he's not in our feeble universe where we see 6s

[@EricMeyerweb]

And then, with the cursor pointing right at the 6, muses “What am I missing?” followed by an awkward silence. I couldn’t help it, I snortchuckled.

[@TheMan83554]

If I didn't think Simon would be a terrible actor, not that I have any evidence, I'd think he was doing it deliberately.

[@dustpan5356]

He complains about the audacity of setters to make him do sudoku, so it should be no surprise he misses simple sudoku things like this 😂

[@inspiringsand123]

Rules: 04:58 Let's Get Cracking: 08:37 Simon's time: 53m01s Puzzle Solved: 1:01:38 What about this video's Top Tier Simarkisms?! Three In the Corner: 6x (42:59, 48:02, 55:50, 55:55, 56:00, 56:07) Bobbins: 4x (53:16, 53:16, 53:16, 57:53) ​Scooby-Doo: 1x (08:41) The Secret: 1x (22:33) Schrödinger Cell: 1x (15:40) You Rotten Thing: 1x (39:58) And how about this video's Simarkisms?! Ah: 20x (12:41, 12:46, 13:39, 14:26, 28:29, 30:28, 30:47, 32:55, 34:57, 37:26, 39:58, 44:46, 49:50, 50:31, 52:13, 52:15, 55:45, 58:51, 59:17, 1:00:19) By Sudoku: 12x (28:57, 29:48, 40:14, 40:35, 42:21, 45:13, 46:07, 57:12, 58:01, 58:26, 59:54, 1:01:32) Hang On: 7x (17:06, 17:08, 18:17, 41:25, 58:49, 58:49, 58:49) Sorry: 6x (15:55, 24:46, 32:35, 49:23, 49:34, 53:27) Pencil Mark/mark: 6x (15:18, 15:21, 35:58, 39:14, 50:37, 52:46) Beautiful: 5x (23:26, 23:28, 35:33, 37:33, 51:24) In Fact: 5x (02:44, 12:54, 15:47, 19:34, 20:01) Clever: 4x (03:47, 06:11, 19:24, 1:00:23) First Digit: 4x (07:06, 07:11, 07:13, 07:15) Obviously: 4x (06:14, 22:58, 23:05, 1:00:14) Lovely: 3x (18:37, 29:46, 1:02:09) Shouting: 3x (02:39, 02:40, 03:57) Symmetry: 3x (18:42, 20:56, 21:32) Naked Single: 2x (49:23, 57:38) Brilliant: 2x (03:44, 1:01:52) Stunning: 2x (1:02:52, 1:02:54) Plonk: 2x (08:52, 26:35) Cake!: 2x (04:00, 04:36) Good Grief: 1x (37:30) What a Puzzle: 1x (1:01:36) Out of Nowhere: 1x (56:30) Naughty: 1x (44:52) I Have no Clue: 1x (12:22) Incredible: 1x (01:29) Gorgeous: 1x (1:02:23) Bonkers: 1x (08:32) If I Trust my Pencil Marks: 1x (50:37) Whoopsie: 1x (11:23) Wow: 1x (43:37) Next Trick: 1x (57:17) What Does This Mean?: 1x (32:27) Nature: 1x (40:31) Most popular number(>9), digit and colour this video: Nineteen (2 mentions) One (107 mentions) Red (72 mentions) Antithesis Battles: Low (26) - High (19) Even (3) - Odd (0) Lower (4) - Higher (2) Black (4) - White (0) Column (48) - Row (37) 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!

[@Mrqwerty2109]

Loves these, keep them going!

[@emo6577]

You and the programmer behind this bot are wonderful,

[@COArSe_D1RTxxx]

Schizophrenic cells

[@erlandodk]

44:44 "What is it I'm missing here?" You're..... literally pointing at it.. 😳😂 We all love Simon for dazzling us with his brilliant logical deductions. His sudoku skills could use some work though 🤪

[@quothacreations]

take a bow, Jay Dyer, that was a virtuoso sudoku--one of the top ten of all time, in my book. it was just the right combination of joy and struggle.

[@Nightknight1992]

the breakin was so much simpler than what simon made it out to be :D every digit can only be marked once, so the 1s in row 1 and column 1 have to be referencing the same cell to avoid 2 marked 1s

[@martysears]

Ah of course! I actually was totally blind to that too and got the break-in by elimination like Simon did. Even after solving the puzzle, then watching Simon solve it, I didn’t think of that til you just explained it 😅

[@Coldheart322]

@@martysears I had a hunch 1 had to be in the corner, and then worked on proving that hunch. Soon came to the same conclusion that trying to put 1 anywhere else on the row or column would break things.

[@JamesTaylor3rd]

Yes, I very quickly saw that, and found myself amazed when Simon simply ruled out all of the other starter numbers instead. It wasn't until the 2nd number, where I knew I had a 4 at one of the ends of the green line but had to work out which one, where I went through all the same calculations Simon used for the 1st digit. I love watching these videos after solving the puzzle to see how Mark or Simon's thinking differs from mine. Amazing puzzle and fantastic video, as always.

[@bertbergers9171]

I don´t remember why i exluded that option from being possible, but after 8 minutes of hard thinking and elimination i broke the puzzle by having two 1´s marked in r6c1 and r1c6. Forgetting that i can only mark 1 of each digit. Thank you for telling tired old me that the only solve to the problem of where r1c1 will hint to without getting 2 equal digits marked.

[@markbennet9058]

At 44:30 a classic "look at the cell where the cursor is" moment ...

[@bobbie0976]

It’s funny to see Simon in total awe for a fog covering the entire grid, when there was one like that just a week ago. I totally enjoy these, find them rather on the easy side of the spectrum. You just know where the break in needs to be, for lack of anything else! But they are lots of fun!!Kudos to the creators!!!

[@masheroz]

But that one had clues outside the grid. This didn't have clues, just rules.

[@achimsinn6189]

I love how Simon needet like 15 Minutes to figure out the first number in the most complicated way possible while it would have been much simpler to figure out, if he remembered that the numbers in the marked cells can't repeat.

[@thunnis2]

44:38 "What is it that i'm missing" as he hovers the 6 xD

[@emilywilliams3237]

Simon, this was wonderful. I just loved it from start to finish, not least of all because you enjoyed it so much. Of course it is also a wonderful puzzle with a very interesting Fog restriction and what a break-in! I will also say that I did NOT notice what so many of the comments in place at the time I am writing this one think is the most amazing thing, which is that you missed a scanning opportunity. I was much more focused on the many logical things you were working out at that time. I remember from some time ago - possibly a year or more - that a commenter mentioned that there are at least two sorts of reasoning required in these more complex sudoku puzzles - the simple logic required to do thorough scanning, and the deeper logic and rigorous reasoning required to get through the several layers in the more complex portions of a puzzle. Switching between those two types of reasoning, said this commenter, is actually non-trivial for the human brain, and thus it is not surprising at all that someone working on the deeper level to solve a complicated thing would miss something on the shallower level, a simple scanning thing. I, for one, am very happy that you get immersed in the deeper part, because I think you love it, and also because I find it so much more interesting and instructive. Thanks so much for your enthusiasm - it is entirely contagious.

[@Stompound]

One of my favorite things about fog of war puzzles is that they give you a good hint on where to look for your next logical deduction. They flow really nicely

[@andrewpalmer5189]

That puzzle was an absolute treat. It took me just over two hours but it was a pleasure all the way. Jay, if you read this comment - nice one, great work.

[@Viva_Reverie]

Took me over 3 hours, but I think this is the first time I've solved a puzzle with a 1+ hour video runtime without any help from the video! Love the fog of war puzzles!

[@zirco77]

There's a really shorter way to break in: row 1 and column 1 need exactly one 1. Whichever column you put 1 in r1, it means the marked digit is right there (itself) in row 1, and symmetrically for the 1 you put in c1. But you can't have two marked 1s on the grid, so the only place put 1 in r1 or c1 is in r1c1. Nevertheless, the time spent by Simon at first isn't lost as those observations allow to break the symmetry (along the diagonal) after you put the first 1.

[@feuerfrosch1920]

this is what i did sometimes u just see it sometimes u dont

[@clarityc481]

Oh, this one was great. 43:36 for me, and I really enjoyed this one. It's rare to have a Fog of War puzzle that jumps around the whole grid like this, but it was really fun unpicking it in all the different areas of the puzzle at once while still leaving certain odd corners fogged out for so long. I'm always a fan of index puzzles, and this was a great one.

[@FelipeRodrigues-vj1zb]

This has got to be my favorite type of variant Sudoku. Absolutely amazing. I've even solved an easier one the other day. PS: that cursor at the 6 at 44 min had me laughing out loud. Never change Simon 😂

[@chocolateboy300]

I finished in 55 minutes. This was one of the most enjoyable Sudokus I have have ever played. The break-in was beautiful, taking me about 28 minutes to figure out. The logic used to figure out where the rest of the marked digits go was beautiful. Finally, the finish with me remembering that all marked digits having to be different led to a beautiful ending. One of the best! Great Puzzle!

[@GuilhermeCarvalhoComposer]

I had first seen this and not even tried to face the puzzle because of the video length. But then I did the "Perfect Miracle", which has similar rules, and suddenly this one became possible. It's a very nice puzzle indeed. Still took me way longer than it should have because once I cleared almost all the fog I kept missing _sudoku_ - of all things.

[@th.nd.r]

Incredibly well set and solved!! I love the concept, the rulesets and how they’re interwoven, and just in general Simon doing a Jay Dyer puzzle, and especially a Fog of War puzzle, will always be great :)

[@Alvarin_IL]

The Whispers line is so much thicker than usual. Wonder how long it has taken to gauge the necessary width for box one break-in :D Such a Simon moment! 44-44 "What is it I'm missing here" -- "YES!"

[@martysears]

I noticed that too... if the lines were any thinner, it would have been too easy to miss the slight slither of line crossing the corner of a cell diagonally

[@martynhill3479]

Even more frustrating was his cursor was in the cell with a 6 in row 7 which would have resolved the 56 he had just placed

[@apiyo_puzzles]

Thank you Simon for the shout out! Chuffed =) And what a puzzle today. Such a clearcut ruleset to start an empty grid, and not a lot of clues beyond. Amazing as ever from Jay.

[@andyjackson2891]

No digits given but completely solvable - amazing puzzle !! Took me a while to get my head around the rule-set and different ending to Simon as '5' on bottom corner is more obvious from 50:00

[@Swisswavey]

45 minutes for me. Incredibly clever puzzle, I loved it. Thanks for sharing it.

[@titusadduxas]

1:48:36 OMG - That was a challenge. I did it on an iPhone and it was really difficult to spot those little green corners! Happy enough to have solved it though. Lovely puzzle.

[@felix_irgendwas]

30:45 for me. Wow, never beaten Simon by such a large amount of time before. Really happy I found that R1C1 must be the marked 1 in the grid almost instantly. The puzzle flowed suuuper smoothly, one of the most enjoyable solves I've ever had. Amazing setting, Jay :)

[@fade2dblack]

Rules: 4:44 Let's get cracking: 8:38

[@SMTRodent]

This is such a complete joy to watch! "Watch this!"

[@Patterner]

the first video ever where "watch this" is *NOT* followed by someone getting hurt

[@ronjohnson6916]

44:32 -- the cursor on the 6 pointing at R7C3. Still loved the solve.

[@juhaloukaja5078]

@40:22, box 7 "marked" digit is 5 - marked digits already used 1, 2 and 8, the box has 3, 4 and 9, and row has 6 and 7 so the only option is 5. That would put a 5 in box 1, leaving a 23 pair on the bottom row of the same box, sorting out the 12 in the whisper in box 2.

[@anpruch]

Oh, such a great puzzle! I absolutely loved solving it. Did it in approximately 101 minutes, but figured out 1 in the first box sooner than Simon. Such a joy to solve!

[@earlmaudrie8650]

I tell you what makes this a lot easier: starting to mark things that CAN'T be a marked cell from the beginning.

[@zuphix1802]

62:42, I was so happy with this one! Extremely fun puzzle, very satisfying to find where you need to look for the next clue. Got a bit overwhelmed at times with the 'eureka' moments, placing the first digit and then finding the second marked cell. Magical.

[@R.a.t.t.y]

If it takes god six days to create everything from the heavens to man, how long does it take a demigod to spot two sixes in the same row?

[@OsefKincaid]

44:40, cursor on the 6 that forces the 56 to be a 5: "What am I missing here?"

[@Cook66]

As a programmer (if that is relevant?), I figured out the first digit as Simon was reading the rules. Usually I can just about figure out what is going on as Simon explains his reasoning, it was fun to be a step ahead for once! Thanks for the videos!

[@benwhite5734]

I intuitively knew the top-left cell was a 1 and was so confident that I just went ahead and wrote it in. Even though I knew it was right (because the fog cleared), I still made myself go through and disprove all the other values before continuing so I wouldn't feel like I'd cheated.

[@fluffycritter]

I got the 1 right away because rather than thinking about what would have been possible there, I thought about where the marked 1 had to go - it would have to go in the first cell in its box, and that would also necessitate the first cell in its row and column to also be 1. Which meant that the 1 *had* to go in the first box.

[@cathybryant5119]

I love that Simon has a favourite cell in the puzzle.

[@MChan75]

Took me 85:09 to finish without any hints, which is not that far off the video length, and I'm proud of myself for that This is a wonderful puzzle, and I never felt truly stuck with the subtle hints, props to the puzzle maker

[@elric58]

It's amazing how he just "sees" some of the most obscure things but routinely misses some of the simplest things! His brain is working on a much higher plane.

[@BVIGrockle]

Definitely helped having seen the miracle video yesterday to go back and solve this. An awesome puzzle!

[@keode]

I may have laughed when Simon completely missed the 6 looking at a 5/6 cell, but I also spent a non-trivial amount of time yelling "YOU CAN'T KNOW THE GERMAN WHIPERS CONNECT" before spotting the sliver of green connecting r2c3 and r3c2, after he got his first digit

[@DasAlbatross]

6 blindness affects thousands of British people every year

[@dancomber9768]

I was very dumfounded by how quickly I was able to do this particular one (22 minutes!). It just all seemed to make sense to me and the indexing was hugely helpful in filling in the grid and clearing the fog. Immediately I knew 1 was top left and box 2 had to be 8 or 9 and box 3 had to be at least 4 and it just got all the marked cell in a couple of minutes.

[@Raven-Creations]

Brilliant, just brilliant. What a hoot to solve. To have a puzzle with no given information except for the rules, and for it to be possible to break in, and for it to have a unique solution was just magical. At the end, I too was left with the red 36 pair, which didn't seem to be resolved by anything. In the end, I noticed that if the one in box 3 were 6, the one in box 8 would also be 6, but I'm not sure if there was something easier I'd missed. Your method was essentially a different manifestation of the same restriction. Blind Simon, the British blues guitarist was in evidence today. When you considered what could go in R7C3, it was a crazy naked single, but you pencil-marked 56, when there's a 6 in the row. You then pointed at the 6, and said "I can't see it". That was stating the bleedin' obvious, as Basil Fawlty might say. You then asked "what is it I'm missing here?" whilst still pointing at the 6. You've been told many times, by numerous people, that you should always look where your pointer is when you're inclined to ask that, because your subconscious seems to know the answer.

[@AndrewJens]

Why wasn't the puzzled called "The Miracle Fog"?

[@CrackingTheCryptic]

Well, it still could be! We could change the video title :)

[@aere481]

great break-in. you can see it easier that 1 can only go in the first position because you can't put multiple 1s in rows 1&9 by indexing. I also thought it finished very strongly. Disambiguating the red cells by interactions with just a few whisper lines was very concise.

[@wristdisabledwriter2893]

I got into the fog thanks to you. I accidentally revealed a fog when trying and I just undid it and pretended not to have seen til I had the not cheating way of finding out. I still needed help from the video thpugh

[@noyadishon6649]

I LOVE fog puzzles!! Can't believe I actually managed to solve it! (In about double Simon's time, but I'm still proud)

[@nk0058]

What a great puzzle! I usually don't understand how to start these but I understood that one had to be the very first digit in one minute then solved the rest in 38 minutes!

[@cassun603]

i really really enjoyed doing this puzzle. The break in was so much fun

[@inwalters]

First time in a while I've een able to comment when the puzzle came out, so I want to repeat my suggestion that on Boxing Day (December 26) [which is a day for switching positions in the UK] I want to see creators like Phistomefel, Aad van de Wetering, Shye, Jay Dyer or Rocky Roer solve puzzles created by Simon and Mark, so they can take a day off.

[@longwaytotipperary]

That’s a great idea 👍🏻

[@chitraagarwal8259]

Also a similar Gas series by those three constructors

[@easy-goingechidna]

Terrific idea!

[@SeriousPigi]

More approachable than the solution time suggests, great puzzle and solve!

[@christinalind2034]

YEEESSSS Fog of war- I love the joy Simon can make out of a FOW- puzzle. Happy days.

[@muzio_gambit]

I actually solved this one by identifying the locations of the marked cells first. As mindblowing as it may be, it is actually possible to prove by contradiction which cells cannot be marked by checking if marking a specific cell would end up yielding conflicting values for its row, column and box "positions". Once enough marked cells have been identified with certainty, the remainder can be found through standard "sudoku rules".

[@ServantOfSatania]

33:51 For me, ironically the biggest hurdle was the sudoku itself after the indicators were done

[@frankthompson9630]

Same for me! I finished in 36:38 with more than half my total time spent on the sudoku.

[@darthrainbows]

What a puzzle! I really enjoyed this one. Solved in 49:33.

[@repsforjesus3563]

Bit of a painful start for everyone who saw the r1c1 restriction at the start 😵 Absolutely lovely video, though! Amazing puzzle

[@soulbound11]

I broke in super easy and quick with unfounded confidence and not checking my logic, but then i got stuck for 25 minutes because i didnt notice the disjointed subset rule for the marked cells. Sneakily placed at the end of the instructions so i still didnt notice it the first two times i checked specifically for it. Beautiful puzzle. It combines three things i love in my sudoku: disjoint subsets, indexing, and my favorite of all time fog of war! Only in puzzles like this do i have any hope of competing time-wise with Simon and his handicap of explaining as he solves :P

[@mikes.8647]

"It is outrageous when these constructors make me do Sudoku at early stages of the puzzle, like 40 minutes in". Simon, 2023

[@Stereomoo]

Pretty happy with getting this done in 1:07, it wasn't easy before or after identifying all the marked cells. I started with r1c1 of course, it was easy to eliminate 2 3 4 5 7 9 but 6 and 8 took me a bit of colouring to be certain of the logic.

[@drewskavich]

A completely fog-filled grid, with nothing visible from the outside. And without an encyclopedic ruleset. 3 cheers. What a wonderful puzzle.

[@kirstenkolkman6758]

This is the first puzzle I watched where I was actually ahead of Simon with some deductions! I feel so smart

[@Jesthers]

Solved all on my own, in about 2 hours! Wonderful puzzle with a marvelous break-in. I recommend this one highly :D

[@shaunholt]

44:10 oooh this was painful. HOW DID HE NOT SEE IT!?!

[@KANPAI666OPPAI]

45:56 - what an interesting puzzle! Usually I don't have the patience for "marked cell" sudokus, but the logic around the 1st r/c/b numbers and how that works along each row / column and box put some clever constraints on where they can go, and then the interplay between the 36 marked pair at the end allowed for an interesting y-wing relationship between the two unsolved regions of cells to disambiguate the rest of it

[@dertigerbauch]

This is my favourite 2023 puzzle so far. Absolutely stunning logic and so much fun

[@Urutsini]

I like that the final solution does have the shaded cells in different places in each box, making Cell 1 in each box different. But didn't need to specify that in the ruleset

[@michaelpdawson]

Love these fog puzzles! Took me a bit over two hours, but I managed to solve it. Fun rule set.

[@MisterM2402]

41:45 for me. Pretty pleased at that, very rare to finish a puzzle from a video over 50 minutes long. I did accidentally see part of Jay Dyer's comment below about the 1s so that gave me a clue as to where to start looking, but I'm sure I would have got there either way!

[@Coyotek4]

34:03 ... once again, I get thorough enjoyment from solve a 'fog' sudoku Wonderful puzzle!

[@LavenderGooms]

Very, very good puzzle. Logicing the breakin is just great. One rule limiting so many digits like that, loved it.

[@petermills5623]

I remember when a sudoku with no given values was cutting edge, now we have no revealed cells at all. Soon itll be sudoku but all the clues stab you

[@alexbove106]

42:25 At this point, you can fill in a 7 in r8c9 because all of the other unknown marked cells see a 7.

[@PauxloE]

What I like to do in these kinds of puzzles (where you need to mark some special cells) is to also highlight all the cells which we know are not marked (in this case likely with a light color like yellow in order to not hide the shadow). This helps in remembering what the index cells can't be.

[@wanderlustwarrior]

40:50 for me. That was fun, and I'm really enjoying these fog of war sudoku with no given light.

[@wanderlustwarrior]

29:17 ths time for me. MUCH better!

[@LeonardLew]

I had such an absurdly hard time with the sudoku part of this one. Absolutely loved the indexing though ❤️

[@Yttria]

Lots of fun. Got stuck at the end not recognizing the corner whisper line couldn't have a 3 because of box 6 and bifurcated the 36 marked boxes to finish. (57:04)

[@wordling720]

37:37! 🎉 I started thinking I'd have to give up, but to my surprise the logical flow was really smooth! (Not surprise because of the setter but because of my lacking ability)

[@joeyday4]

I got stuck for several minutes right where Simon was at 59:05. I'm astonished he was able to work it out logically so quickly, and he even said there is probably an easier way. I don't know if my way is easier, and really it relies on the same logic anyway, but here was my thinking: I thought there must be a Y-wing in the puzzle somewhere, what with all the 1's and 3's and 6's. But try as I might I couldn't find one. But then I realized (just as Simon did) because of the 36 pair in the disjoint set of marked cells, that meant that r2c8 and r8c4 were sort of "quantum entangled", i.e. must have the same value (Simon actually found three cells, but I only noticed the two). Then I found what I can only describe as a "spooky Y-wing at a distance". If r2c8/r8c4 are a 3, then r6c8 must be a 1, but if r2c8/r8c4 are a 6, then r8c2 is a 1, so anything that sees both r6c8 and r8c2 can't be a 1, and r6c2 can see them both, therefore it must not be a 1 but rather a 6, and that broke the rest of the puzzle for me. I love how the very last trick came down to the special marked cells we built so early in the solution. What a brilliant brilliant puzzle.

[@michaeldakin1474]

I resolved it a little differently at the end, when you’re left with all the 1-3-6 combinations - I looked at r8c2, and discovered that it would have the same value whatever the order of the 3-6 pair in the marked cells, so I went from there.

[@FleursetRebellion]

Wow, amazing one! I made it through the whole thing in 2 hours (which is an okay time for me) and I only got seriously hung up on the deduction of the 1 in the bottom-right corner. I had to use your video to get the hint on that part, so thanks for that!

[@robert-skibelo]

42:25 You need to look around whenever you place a digit. The moment 7 is placed in r2c5, r8c9 is the only marked cell that can contain a 7. 44:18 Strange blindness at this point - pencilling 5 and 6 into r7c3! Can't you see the 6 in r7c7?!

[@bchandler8945]

I was basically screaming at my phone for that logic behind the Red marked 9 haha, good solve

[@EelcoWind]

Curse you, CtC! I needed to go to bed early tonight because of an early rise in the morning, and then you come at me with a Sudoku with no visible clues at all... Luckily I managed it barely within the hour, but still off to bed too late ^^ This was a very enjoyable one, though. Worth it, I'll just chuck an extra cup of coffee in the morning, I guess :)

[@PauxloE]

I got stuck for a long time in a situation where I got 33 digits in the grid, all marked cells (and digits in 6 of the marked ones), everything but 7 cells (in row 9 and column 9) revealed, and everything fully pencil-marked. After 185 minutes, I decided to watch the video, maybe Simon spots some swordfish or similar higher level logic. And after some minutes of Simon theorizing about entropy, I noticed that I had a 56 pair in the first row which was determined by the position of the marked cells forever. Doh! (What Simon resolved at 38:36.) This allowed me to finish it off. (Ended with a extensive deadly pattern, where a 36 pair of marked cells helped to resolve it. Nice.) 199:22 in total, with solve counter 464.

[@CrankyOtter]

This was fun to do. Couple years ago I would never have been able to do a no cells given sudoku. I need need Simon to interpret the rules, but once I got the hang of it it went well.

[@danielepicone1480]

It is quite funny how the break-in of a digitless puzzle was many times easier than the ending, where you have basically already filled 85% of the grid. Finished in 55m25s.

[@gotbread2]

The logic in this was brilliant. I liked that ruleset a lot. one of the few i could solve (although i had to take some simon-help here and there).

[@FrancisFjordCupola]

59:06 "I got a 16-pair here, so this has become an 8..." said Simon. But at 54:15 he filled in the 8 on the 7th row and if only he'd scanned box 4, he could have seen that 8 could only be in one spot because of Sudoku. Which would then as a knock-on effect give the other eights and clear the far right diagonal green line in box 6. Scanning requires such focus and attention, and it's so easy to overlook. I hope some day, some setter will be naughty and deliver a sudoku that alternates between coming up with a genius deduction and Sudoku scanning to make progress in solving it. I'm mean.

[@hargrim6892]

gorgeous setting of the puzzle ❤

[@josephprozinski9311]

I think instead of calling it a "pencil marked cell" you should call it a "Mark penciled cell"

[@anthonydinozzoable]

The connections at 54:00 and 1:00:00 took me about an hour to make. The rest of the puzzle was no problem, but these are just so hard to visualize!

[@dertigerbauch]

44:32 Hovering the cursor over the bloody 6 for 15 seconds made me incredibly nervous 😵‍💫

[@jakezanders6598]

Got really hung up at 59:45. Took me well over 100 minutes to solve, but as soon as I hit that point, I had to go to the video and watch to get the solution. I can follow Simons logic, but couldn't get there myself, and I'd really love to know if there was an easier way to solve those 3/6 pairs

[@srwapo]

42:02, I got the break in, but I got stuck and had to look to see what I was missing. Turns out r3c5 isn't a marked cell because it could only be a 1 or a 2 and 1 and 2 were already marked!