Can You Solve The Impossible Sudoku?

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** TODAY'S PUZZLE **
Happy Birthday RockyRoer! Simon attempts RockyRoer's astonishing What Do Killers Eat? sudoku - a puzzle with a remarkable lack of digits. This one is absolutely stunning though so do give it a go if you can!
Play the puzzle at the link below:
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Rules:
Normal sudoku rules apply. In cages, digits cannot repeat. The digits in each cage sum to the “cage total”. Clues outside of the grid (“Sandwich totals”) are the sum of the digits between the 1 and 9 in their row/column. In every row and column containing a “?”, the sandwich total will be equal to one of the cage totals in that row/column. Nothing is known about rows/columns with no ? clue. EG Row 7's sandwich total is either equal to the cage total from column 1's 7-cell cage, the 8-cell L shaped cage in column 2, the 4 cell cage in column 3, the 2 cell cage in Box 8, the 5 cell cage in boxes 5/8, or the 9 cell cage in boxes 8 and 9.
** OCTOBER MONTHLY REWARD - OUT NOW **
The Duality Sudoku Hunt is just out. Massive thanks and kudos to the Sudoku Skunkworks for creating such a brilliant set of puzzles (14 in all!). You'll be able to enter the competition if you can solve the first 4 sudokus. If you solve all 14, you'll get a shoutout.
We've also just released Simon & Mark's solve of Vignettes by zetamath, which you can play at the link below:
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[@sorchahannah288]

Simon, I am a professional cake decorator and regularly listen to you solve while making cakes. Your commitment to wishing your fans a happy birthday and reminding them of the importance of cake always makes my day! ❤

[@RichSmith77]

It's insane, and I love it. It's a sudoku - with no given digits. It's a killer sudoku - with no given cage totals. It's a sandwich sudoku - with no given sandwich totals. The concept is insane, the execution is remarkable, and its existence is almost beyond belief. (And to cap it all, I was actually able to solve it 😂)

[@amysteele2488]

Very nicely summed up, and congrats on the solve!

[@joshtiley3460]

If Alexa gained sentience based on the information she has learned she would introduce herself as Bilbo Bobbins, make “somewhat useless deductions”, have a best friend called Maverick and drink wine.

[@SkyBlue-cv8qb]

11:30 "That is as useful as a chocolate teapot" probably my favourite simonism of the day

[@AlRoderick]

That one's a markism that Simon's adopted, although it's a known idiom.

[@amysteele2488]

Simon 1:08:30 :"So the world is making sense, even if it is quite a complicated world". This is exactly what I love about CtC!

[@longwaytotipperary]

Same!

[@davidrattner9]

Perfect way to sum it up Amy!! Every day something different to make us love CtC! Like peeling back an onion and exposing all its layers and fine details.

[@longwaytotipperary]

@@davidrattner9 true that!

[@zmaj12321]

That's a beautiful line.

[@iiiiimoaN]

"Can you solve the impossible sudoku?" No, but I'm gonna watch Simon do it! 😁

[@longwaytotipperary]

Ditto!😁

[@malvoliosf]

“Can you solve the impossible sudoku?” By definition, no.

[@doublelxp]

I consider it a minor victory if I can follow the logic.

[@Manigo1743]

@@malvoliosf No youtuber knows what the word impossible means.

[@Orenotter]

Sandwiches that were mere questions, Cages with zero suggestions, But still we were hoping He'd solve it with roping. He did! Now that's worth our attention!

[@inspiringsand123]

Rules: 06:15 Let's Get Cracking: 09:56 What about this video's Top Tier Simarkisms?! The Secret: 6x (10:05, 10:10, 10:19, 10:21, 10:23, 10:26) Bobbins: 5x (46:03, 1:10:34, 1:10:34, 1:10:34, 1:10:34) Chocolate Teapot: 1x (11:30) ​Scooby-Doo: 1x (46:17) And how about this video's Simarkisms?! Ah: 11x (11:53, 30:33, 33:58, 34:10, 35:10, 38:02, 41:57, 46:29, 52:41, 1:05:28, 1:13:56) Beautiful: 9x (04:50, 30:23, 30:27, 41:57, 46:51, 53:10, 1:06:34, 1:06:50, 1:15:12) By Sudoku: 8x (30:47, 35:43, 39:45, 42:42, 59:26, 1:08:04, 1:09:01, 1:09:56) Hang On: 8x (04:37, 17:47, 25:13, 54:33, 54:33, 57:00, 1:01:15, 1:04:44) In Fact: 7x (04:04, 19:00, 25:26, 32:28, 41:38, 1:02:33, 1:10:11) Clever: 5x (36:22, 36:25, 42:00, 47:13, 47:13) Good Grief: 4x (07:07, 53:10, 53:13, 54:07) Sorry: 4x (32:23, 1:01:46, 1:03:58, 1:05:36) Lovely: 4x (36:13, 38:05, 38:05, 1:17:18) Obviously: 4x (00:42, 18:51, 21:32, 27:05) What on Earth: 3x (47:21, 49:48, 58:42) Deadly Pattern: 3x (1:11:27, 1:12:45, 1:14:18) What Does This Mean?: 3x (20:18, 26:43, 46:12) Naughty: 2x (56:50, 58:29) I Have no Clue: 2x (29:07) Break the Puzzle: 2x (25:53, 1:05:23) Ridiculous: 2x (16:12, 16:16) I've Got It!: 2x (30:23, 38:02) Wow: 2x (19:30, 1:06:26) Cake!: 2x (00:42, 01:29) Axiomatically: 1x (39:02) Out of Nowhere: 1x (54:07) Nonsense: 1x (19:30) Stuck: 1x (49:41) Brilliant: 1x (25:33) Fascinating: 1x (02:50) Extraordinary: 1x (04:27) Going Mad: 1x (1:03:55) Shouting: 1x (01:17) Epiphany: 1x (40:04) Of All Things: 1x (1:09:51) Masterpiece: 1x (00:59) Magnificent: 1x (26:30) Stunning: 1x (1:17:20) Unbelievable: 1x (1:16:52) Alexa: 1x (20:10) I Digress: 1x (18:08) Baffling: 1x (50:12) Gobsmacked: 1x (09:48) Pencil Mark/mark: 1x (14:22) Most popular number(>9), digit and colour this video: Fifteen (22 mentions) One (118 mentions) Green (41 mentions) Antithesis Battles: Low (3) - High (0) Even (7) - Odd (0) Outside (3) - Inside (2) Column (38) - Row (33) 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!

[@th.nd.r]

That’s spectacular setting and solving!!! My favorite moment in the solve was probably the series of things that happens after like the 52 minute mark. I’m just shocked at how RockyRoer was able to create this, as well as by how quickly and well Simon was able to solve this intimidating beast. I also compiled my favorite quotes from the solve: - No! Do not - it’s a secret! You gotta keep it secret, that’s your competitive advantage when you’re solving sudoku! - But triple digit sandwiches are off the menu now! - The way to do this is not to think about red herrings; it’s to think about red cells! - So the world is making sense, even if it is a quite complicated world. - I tried to do it with some sort of aplomb, and I probably failed, but I did have a wonderful time on the journey.

[@srwapo]

@39:21, yeah, a five cell cage can equal 15 IF IT DIDN'T ALREADY HAVE A 9 IN IT! Your minimum is 19.

[@leoniesmith5925]

Thank you for the birthday wishes!! 🎉 There certainly was a lot of cake 😋

[@spatulamahn]

"I can't tell you which cage it references cause it could add up to 15" as he stares clearly at the 9 he has already put in the 5-digit, impossible to now be 15, cage. :) Simon being Simon - lol

[@Tony_Regime]

sometimes Simon can't see the wood for the trees

[@marklindsey1995]

Simon: Let's choose colors wisely to help the color blind Also Simon: OCD people, I left a present for you in row 9!

[@shellmichael9665]

I was so let down by that. Lmao

[@jamesrhodes3763]

It's a shame, because that would have been very beautiful logic.

[@emilywilliams3237]

I agree, it looked impossible to be a solvable puzzle. But as you so often do, Simon, you made it look easy. Thanks so much for this. Looking forward to the kickstarter tomorrow!

[@GrahamNicholson56]

1:44 If you like mechanical pencils, try the Uni Kuru Toga pencils. The mechanism rotates the lead as you write, giving you a sharp point at all times. An absolute joy to use!

[@longwaytotipperary]

I love mechanical pencils - I’ll look for those.

[@SilverEchoes]

Yes, Kuru Toga pencils! They often release special edition colors or patterns, too - like Harry Potter, Disney, and Studio Ghibli. Amazon tends to have the standard line, but a specialty pen shop (like JetPens or Tokyo Pen Shop, for those in the US) will carry the limited prints.

[@pantheracheshire]

Dear Simon, for the other puzzle, you don't need to "record" in the circles -- very doable without it! Just put it in your software with blank circles! :)

[@18stupefy]

Simon sharing his Acer tree is so wholesome and filled me with joy!

[@Jodawo]

What a brutally beautiful puzzle. I think this one should be considered for the new book. The logic was so embedded into the puzzle. Just looking at it it's hard to believe this could actually exist and have a unique solution. Hard to believe at the end that you could take out one of the question marks and still have a logical solve. It's sometimes scary how Simon can solve these puzzles that look so daunting.

[@RichSmith77]

A few others have pointed out he did use those question marks in columns 7 and 8 when colouring cells green next to an identified crust, because they couldn't be zero sandwich clues. So they they might be necessary after all.

[@Jodawo]

@@RichSmith77 That doesn't make any sense. It probably was necessary because of the solve path that the Setter used. Simon's solve probably took a different path that made both of the "?'s" unnecessary. If you watch the video you will see that those two "?'s" were not even used until the end. Only one of them was necessary to disambiguate the deadly pattern and either could have done it. It's a beautiful puzzle and it's an amazing construction. Having an extra "?" does not diminish the puzzle but actually makes it more amazing that one less clue could have been used.

[@rontyson6118]

@@RichSmith77 I see what they were saying. It does make sense. 👍

[@RichSmith77]

@@Jodawo At 42:55 Simon used the question mark in column 8 to colour two cells next to the 9 green. At 59:35 he similarly uses the question mark in column 7 to colour the two cells next to another 9 green. It could be that there's a path through that doesn't require those steps, but my original point was that Simon's solve path did use both question marks at various points, so we cannot use Simon's solve to say one of those question marks may not have been necessary.

[@BryanLu0]

@@Jodawo If the ?s were removed the sandwich total could be 0

[@davidrattner9]

Beautiful, sublime, extraordinary puzzle from you rocky roer and hope you had a wonderful birthday!!!

[@hubertnnn]

For the circles, the easy way would be to mark the circles A,B,C,D... and then add a dictionary to the right, similar to how you did in one of the previous puzzles. It might not be as easy to scan, but at least it gives you a way to solve it.

[@connorbrown3588]

Sometimes I think I'm good at sudoku but then I watch you solve puzzles like this to put me back in my place. I think it would have taken me twice as long to solve this one. 😂

[@wariolandgoldpiramid]

This was a beautiful puzzle. From the way the sandwhich-cage interactions gave us deductions in just so slightly different ways at the start, to the brilliant Rope-ing in rows 7-9 caused by a tricky placed 9-cell "45" cage , the clever uncaged cell in box 3, and the two final ?-marks in columns 7 and 8, which just helped us resolve the final deadly pattern (although, we're they both needed, or could the puzzle have gotten rid of the ?-mark above the column 8?). So many brilliant logics. I loved this. Take a bow, RockyRoer. Happy Birthday!

[@BryanLu0]

I believe both are needed because in rows with ?s 1s can't go directly next to 9s

[@mouseglove5341]

they both were needed as non-zero sandwich clues

[@JalebJay]

43:13 Kinda amazing that less than a minute after he points out the restriction of 9 repeating in cages, he immediately misses 1 repeating in that 9 cage.

[@tremkl]

Either one of the final ?s could have resolved the 34 pairs. You did use both of them earlier in the puzzle to green cells, so I suspect the puzzle needs both, but only one is needed at the end for the deadly pattern.

[@Ruddigore]

This is truly a magnificent solve by Simon, way out of my pay scale and bordering on Wizardry. Thank you for everything Simon and Mark put out and I can't wait to order volume two of the CTC book; not to complete them but just to know that I'm in possession of the greatest sudoku puzzles on the planet.

[@Ardalambdion]

The weirder the ruleset, the more Simon is attracted to it...

[@JonnyKaufmanTenor]

WOW WOW WOW. I loved solving this puzzle! Rocky Roer giving a gift to us on his birthday. Brilliant puzzle. Brilliant man. Still in awe...👏👏👏🥳

[@BenRHarsh]

Simon: Solves this puzzle. Also Simon: A 5 cell cage (containing a placed 9) could add up to 15 and could be a matching cage total for a 2 cell sandwich containing a 2 cell cage. Simon is the embodiment of 'missing the forest for the trees' at times and its great.

[@Yoanka]

It's been a while since I've checked up on this channel. As always, it's such a delight to put on one of your videos while doing chores. :)

[@Kradlum]

A mindboggling puzzle and solve!

[@nibletsgo599]

55:09 for me! I'm always especially excited when Simon calls the sudoku impossible. I used a lot more colors than Simon did to track the possible cages for each sandwich clue and just used the pen tool X's to track which cells can't be 1 or 9.

[@Tringard]

Finally found the time to dedicate to this and really enjoyed the logic and flow of it.

[@ericpraline1302]

Great stuff. Some of the logic which emerges from these interesting rule sets is quite surprising and elegant. I also liked the way that sudoku periodically helped out.

[@jonbrowne8334]

Beyond understating but appreciate the solve! Thanks

[@longwaytotipperary]

Happy Birthday RockyRoer !🎂. Simon - what a glorious tree! I think that color is “vermilion.”

[@davidrattner9]

I would concur with you that is a wise choice for the color. :-)

[@longwaytotipperary]

@@davidrattner9 🙂

[@domcactus]

One of my favorites this year, it was a delightful solve

[@leprechaun_33]

Oh, wow. It was a nice surprise hearing a happy birthday wish to someone from Kazakhstan! Қаныш туған күні қутты болсын!

[@Rubrickety]

This is one of my prouder solves. Amazing puzzle.

[@markp7262]

1:01:05 finish. I concentrated on pencil marking 1s and 9s early, so I could use the colors to code the cages (grey for unusable, and no repeat colors in clued rows/columns). This helped me to more easily identify potential cages to match to the clues. Awesome puzzle!

[@Swisswavey]

Nice puzzle. Just under 50 minutes for me. Really interesting ruleset. Very enjoyable.

[@fuipig]

I really really liked solving this one (70 minutes). What an amazing puzzle. Goes to my favourite list along with that monopoly-sudoku a few months ago

[@Deadman7433]

Simon this is a very impressive solve. Well done sir

[@TheeEJ2H]

I was grinning by the end of this as the column 7 clue came into its own- great solve!

[@pixllo]

43:08 for me, the setting was brilliant, there is never a dull moment

[@gatlygat]

This puzzle is truly one of the all time greats. (And said knowing the stratospheric level of its competition) Will be thinking about this jawdropper for days and weeks to come. Rockyroer is such a brilliant constructor, I shouldn't be surprised. But I am, because I can't quite believe this exists.

[@andykillsu]

Finally a Sandwich sudoku!! It’s been ages since we had one and I really started missing it

[@wanderlustwarrior]

1:08:32 For me. Whew, that was fun. I'm really happy I'm actually completing these hour long puzzles!

[@dragonspight]

That was a fun puzzle. Clocked in at 102:30 with breaks. This is probably the best example of roping logic I've seen used in a puzzle.

[@Gonzalo_Garcia_]

25:35 for me. Absolutely incredible solve path, what a fantastic puzzle.

[@KinkyTurtle]

Whew! That was a mental workout!

[@markjreed]

There is of course a wide range of types and degrees of "colorblindness", but the folks I know have a much harder time with green and orange than green and red.

[@Coyotek4]

1:19:14 ... I took a break after about 30 minutes, having broke a few times; when I returned, I finally saw my error and was able to proceed. Made another error late, but caught it before I started over again. A truly phenomenal puzzle! My mind is blown!

[@deanvoets8091]

Omg what a puzzle thanks! 80 mins in and not really much progress but I'm intrigued. I think I will take some time over the coming days to try to solve it before watching the video. Actually after like an hour I felt I finally had a breakthrough. 5 mins later I notice it is broken. Restart (keeping timer) and I hit the same issue although my logic feels right. I guess one more try today and then I continue tomorrow. Thanks for your videos. As probably many I started watching with the miracle sudoku puzzle. I don't watch all of them but I often come back to this channel and you got me into sudoku :). Ok, enough brake. Let's attack that puzzle again.

[@christophstahl8169]

Absolutly stunning puzzle (and solve, as usual). I did use the two ? sandwich clues in the end. I didn't use the cell outside the killer cages to deduct that it needs to be a 3. That felt very clever when Simon did it. But also deliberate from a puzzle setting point of view, since it is the only cell not in a cage. Since i solved the two sandwich clues earlier, i didn't get to the deadly pattern. And that is a really lovely ending to the puzzle, so i would remove one of those two sandwich clues. Surprisingly this puzzle was not too difficult. It looked daunting to start but I started in row one, then column one and then I got going right away. Really lovely flow. Enjoyed it a bunch.

[@Wildhorn666]

@39:32 Why could it not reference the D cage?

[@RichSmith77]

It looks like it could be. I'm not too sure why Simon skipped that cage (cage D) when working his way along the row from 37:54. It doesn't make any difference, though. It's four cells, so a minimum of 10, which still means the sandwich clue in that row couldn't be one cell, so still pushed the 9 out to r7c6. And once you have the crusts surrounding the two cell cage between them, it doesn't really matter if another cage also matches the sandwich total. Cage D can be ignored for the same reason as the cage up into box 5. You only need one cage to match, and the two cell cage will match, whatever.

[@FleckerMan]

You could letter the circles and have a two column, 6 cell wide section to the right with the letters for each circle and space for two digits after each - need 10 rows but it'd fit, just about :)

[@troymcdougal9010]

The solution to the circle puzzle conundrum: Give it to Sven; he can do anything!!!!

[@petartsankov8655]

3:10 for the puzzle you could use an 8 by 8 board to mark down what is inside of the circles, with the cells where no circles exist being blacked out and ofcourse another board for the rest of the puzzle

[@tsgsjeremy]

Dismissing row 9 as nonsense added at least 20 minutes to the solve. R9C1 is a forced digit. Then the shape of the cages in box 9 lead to filling in possible locations of 1's and 9's across boxes 7, 8 and 9. And we're off! LOL

[@olafkonrad7168]

I think the color of that bush is called vermilion. It seems to be a color-blind friendly replacement for red.

[@davidkay6655]

I'm red green colour blind but in your palate thay are fine I struggle with green and yellow and purple and blue both look identical regards David

[@RichSmith77]

He tries to be considerate to the colour blind in his audience, yet he still chose purple and blue for two of the colours when showing the roping in the bottom three rows. I've seen plenty of past comments saying those are the worst pairing, but it doesn't seem that Simon has taken it in. I don't know why.

[@davidkay6655]

@@RichSmith77unfortunately if you're like me and watch the videos a few hours later or even the next day then your comments don't get seen because simon and mark are busy and have already move on

[@RichSmith77]

@@davidkay6655 True. Simon used to regularly claim he read "all the comments". I've only ever seen channel likes/replies to comments posted within the first few hours of the video being posted. I don't think it would even be possible to read all the comments posted, possibly days or months after the video was uploaded. 🙂

[@brenthoskisson6979]

I love how the "roping" IS the logic - rather than a result of the logic as most sudokus do.

[@ssbm4ever]

even if I spend the rest of my life on these kind of puzzle, I wouldnt succeed. Its ridiculous how good some people are in solving those!

[@BookofAeons]

The clues that seemed "unnecessary" were used to eliminate the possibility of 0 sums during the solve.

[@selenasilverstep7981]

Specifically at 42:50. The question mark in column 7 was similarly used at 59:30.

[@nwdreamer]

*Sheesh!* What's next??? A completely blank puzzle where the rules only say the numbers must be entered as primes that circle around the grid? 😮 Phistomefel: "Hold my Uni Kuru Toga pencil!" 😁

[@lexyeevee]

dang. i was actually speeding along twice as fast as simon on this one, somehow, but early on i assumed a 1 had to go in r9c8 and that only caused a mysterious problem half an hour later, at which point i had to check the video :)

[@jonsick445]

2hrs 47mins. First unassisted sandwich sudoku solve as I usually don't get on well with them at all. Definitely picked the right one to start with. I had Napalm Death and Slayer CDs to see me through. I definitely need a nap!

[@williambarnes3868]

If it is impossible then , by definition it CANNOT be solved!

[@f.b.jeffers0n]

Colour blind here, and you're right. Blue and purple \ green and yellow are the only two tricky colour sets, when used in combo...

[@yourcan]

I find the green and orange to be indistinguishable from each other

[@davehislop6978]

First rule of the secret, don’t talk about the secret! Tut tut Mark!

[@user-ox9oo6wp6d]

35:26 for me. I have played a sudoku before which rule set is something like "?" indicates the X-sum total and Sandwich total are the same in that row/column. The overlapping areas are quite crusial to solve these puzzles.

[@timcotton1782]

I got the 9 in R9C1 immediately, knowing that it had to be a 'crust' digit, and that having a 9 in the cage giving the sandwich total could not work. The single digit in R9C2 has to be greater than the digit(s) outside of the sandwich on the right end of the cage by the amount of the 'crust' digit inside the cage. Since the cage total is at least 28, there is no way to accomplish that feat unless the crust digit inside the cage is 1. This then immediately places the 9 in R2C2, since R1C1 must be a crust digit and no cage total is zero, so R1C2 could never be a crust digit. My speedy brilliance came to a brutal end shortly after that, and it took severe plodding to progress to a solution.

[@MarushiaDark316]

Poor Simon always seems to get the hour-long solves.

[@jeffreyrosas1784]

31:13 once you have the 9’s in row 1 and 2 the only place in the 9-cell cage in rows 2 and 3 that does not “see” a 9 is row 3 column 8. A green cell on either side, and the 1 in column 4 or 5. There has to be a reason for the cageless cell in R3C6. I see you saw it at 42:52 38:54 once you place a 9 you can green-ify all orthogonally connected squares. That would get rid of half the 1s still lingering around 20 minutes later in row 8 column 6 (putting in in r4) and making r8c5 a 1, which, when you get the 1 in column 6 will give all the 1s 49:10 8 in R2C1 means an 8 in row 3 in the aardvark-shaped cage in box 2 and 3 and row 1 cage 3. Takes the 8 pencil mark out of R3C9 56:06 4 in row 2 column 3 puts a 4 in row 3 in the aardvark shaped cage in box 2, which eliminates 4 in the cageless cell, which would eliminate the “bobbins bobbins bobbins” at 1:10:36

[@Drewsparkwhitworth]

Triple digit sandwiches are *off* the menu 😂

[@Qsalis]

I think it's more that the colours are different enough on other wavelengths and brightmess so they're still discernible

[@howmanyrobot]

You may have used that other question mark to give you a necessary green sandwich cell at some point.

[@elijahmoore1691]

As a red/green colorblind representative, it's all good!

[@tyomytch9945]

Did you know that... A pattern of nines in boxes 369 at 42:35 is actually called "Ж-wing".

[@skymotel2]

I am a draughtsman.... Mechanical pencils are evil.... Give me a traditional 4H wooden pencil everyday!

[@kielblanton]

A deadly pattern is, by definition, not able to be solved with normal sudoku. Simon identifies the 34 deadly pattern in the middle rows, and then is repeatedly surprised that writing in 3s and 4s in the puzzle doesn't solve the pattern via normal sudoku. Found that pretty humorous.

[@stevieinselby]

It wouldn't be a good puzzle if it didn't result in Simon thinking he had broken it by getting a deadly pattern at some point in the solve 😆

[@andrewgrant6516]

Small point and hard to notice, but r3c7 isn't actually a cage, and thus can't be a cage total or a sandwich total.

[@RichSmith77]

I know the puzzle solves so it's not a sandwich total, but is their an axiomatic reason why it couldn't have been a sandwich total just because it wasn't in a cage?

[@rockyroerNPC]

That was most definitely intentional. I left that cell uncaged on purpose to force the 1 not next to it. I had hoped that the absence of a cage would be noticeable since every other cell was caged.

[@AhsimNreiziev]

At 39:17, Simon seems to believe that a 5-cell cage with a 9 in it can add up to as little as 15, when in fact of course the minimum is 19 (1 + 2 + 3 + 4 + 9)..........

[@timcotton1782]

Stormtrooper scanning strikes again. When Simon placed the 9 in R3C8 and surrounded it with green cells, forcing the 1 candidates for Row1 into Box2, it prevents a 1 from being placed at R2C7, as they are in the same cage. Then he agonized over whether the 1 in Row2 could actually work in Col9, when it had no other choice...

[@jl2399]

Awesome puzzle. You can immediately infer that R9C1 is a 9, because you need space between the 1/9 anchor on the left and the 7-cell box, in order to cancel out your 1/9 anchor on the right (inside the box) and everything to the right of it. Since R9C2 is the only spacer cell available to do this canceling out, and we know its max value is 8, the left anchor has to be in R9C1 and has to be the 9.

[@Raven-Creations]

For a change, I'm writing this before watching your solve. Any of your usual transgressions will be forgiven, because it's sure to bamboozle you, and since you obviously solved it, you've earned yourself a nag-free day. The break-in for me was C1, where the sandwich sum had to be the 7-cell cage, but it also has to be the sandwich filling, so had to be 35. The R9 sum had to be given by the 7-cell cage, which had to contain 1, so R9C1=9. R9C2 had to equal the outies+1, so the outies could only be one or two cells. In R1, the sum was given by R1C9, and had to be capable of being a 2-cell sandwich filling, so was 5678, with R1C4=9. Because of the non-crust at the top of C2, R2C2 (which must be the sum) is now the only place for 9, with 1 in either R5 or R6. 1 in C3 must be in R7, because the 1s in R9 mean 1 in the 9-cell cage is in R8 in box 8. If R4C3 were 9, then the filling is a single cell, whose sum is given by the 3-cell cage. However, that can't contain a 1, which it would have to. Therefore, R4C3=9. We now have a filling which is at most 15, and is given by the 3-cell cage above, which already contains 9 and can't include 1, so it must be 14 or 15. The only place for 9 in the 9-cell cage in boxes 2/3 is R3C8. The geometry of that cage means R1C5/6 go into R2C7/8, leaving three places in the box for 1, but two of those are next to the 9 so can be ruled out. The shape of the 9-cell cage in box 8/9 forces roping across the bottom three boxes, so the 9 from R9C1 appears in R7C5/6, and in R8C7/9 (but not above the 1). In box 6, 1 is now in the 2x2 R5/6C7/8, aligning with the 1s in box 4, so in box 5 1 is in R5. In R7, if the 9 was in C5, the filling would be a single digit, but none of the cages can sum to less than 9, so the 9 goes in C6, and the sandwich filling is also the sum. The puzzle is virtually solving itself (he lied)! This was a fascinating and really enjoyable hunt. The above steps, and getting the rest of the 1s and 9s, did come fairly easily, but the rest was quite a grind. There wasn't too much in the way of difficult logic, but spotting the next weak point was challenging. For instance, noticing that the options for one cage pushed it just out of range to be a clue for a specific sandwich was pretty hard work. Those confounded un-clued rows and columns! I lost count of the number of times I tried to work out some sandwich=cage logic on them. Fortunately, I never quite got as far as pencil-marking, but very nearly made R7C5=R2C4 because the 2-cell cage in box 5 was the only candidate for a sum. At one point I tried it on column 9, and thought I was close to a breakthrough because of the interaction with R9. Only when it broke down, and I thought I'd broken the puzzle did I realise my mistake. I'll remember this one for quite a while. It's a great candidate for the new book. Rocky's first puzzle on the channel was good, but I don't recall it being that hard. I think his next was a bit tougher. Typical maths teacher, always ramping up the difficulty! Just as you've mastered your 2 times table, he spoils your day by telling you there's a 3 times table, and you need to learn that too. Before you know it, you're calculating eigenvectors and Laplace transforms, but if you don't keep up, you're utterly lost and bewildered. We all owe it to ourselves to keep up with Rocky. We can't let the maths teacher win.

[@purplezart]

can the software fit a 17x17 grid?

[@stevieinselby]

_Can You Solve The Impossible Sudoku?_ I'm going to go with Betteridge's Law of Headlines: "Any headline that ends in a question mark can be answered by the word no" 😆

[@arthurcharest9061]

Could the 8 in box 7 have been placed because of the roping and the 68 pair in box 9?

[@chessburns]

Those of u who could solve this puzzle my hats off to u. I would not have been able to. How Simon and Mark solve these puzzles is beyond me. Especially Simon with the "wrogn video" series. I can understand how Simon solves those with pure logic. But this puzzle belongs in a frame once its solved because this puzzle has to b up there with the wrogn solves in terms of its logic. I would love to peek inside Simon's brain and admire the beauty in it. Simon guts out the toughest of the toughest solves known to man in the Sudoku world. My absolute favorite puzzles he solves aside from the wrogn ones is the chess themed puzzles. That said wonderful puzzle.

[@dariobarisic3502]

Hey man! I would genuinely suggest trying these kind of puzzles on your own. Even if you are not able to solve it at the end, it's a really good exercise for your brain and I'm sure you will progress and eventually be able to solve these "more difficult" puzzles. I remember when I just started watching this channel (like a year ago) it took me sometimes 2+ hours for more difficult puzzles (and some I wouldn't be able to solve at all). I'm happy to say that my times have drastically improved since then just through trying to solve on my own. Watching the solve is surely helpful as well, but not to the same extent.

[@G.Aaron.Fisher]

LMAO at the Phoenix Wright thumbnail.

[@jessevennard2640]

Who else got stuck wondering if cageless R3C7 was intentional? On the path I took, it was significant enough to ponder. If intentional, it proved I could have two sandwich clues indicating the same cage (which I was unsure of) if unintentional, it was a perfectly placed mistake because although I didn’t use it, it worked. This puzzle is worthy of any and all accolades. Smart.

[@jonnybolton4659]

1:05:47 for me. I think it's the first time I've successfully solved a particularly difficult puzzle (1 hour plus video) without watching the video for hints!

[@myfyrmadocjones]

What’s happened to Inspiring Sand?

[@hyperactvehuman]

Q: Can you solve the impossible sudoku? Answer: *Clicks the video. Realizes it is 77mins.* No. I can't. :|

[@de8o]

My thoughts exactly 🤣

[@jeffreygi]

Tutor is usually one to one

[@Vendavalez]

3:00 I am curious, is the software that you use open source? Because software can be made to do anything if you're willing to write the code to make it do it. Plus I have been really curious about how it is written.

[@Grandy_UiD]

"Chad anime Simon isn't real, he can't make you gay for him." the thumbnails of the last few videos: "Hello there..."

[@StarClan4evr]

Completely broke this puzzle after spending 5 hours on it because I didn't know what roping was, as Simon called it. I don't think I have the will to restart. I usually like puzzles that make me do big spreadsheets with math, but I spent so long on this that I all I feel is tired. Edit: Clicked undo a lot until I felt like I could account for the roping, literally solved it in another 40 minutes. I like complimenting puzzles on the parts that stood out the most to me, but I can't remember anything from about 6 hours ago, it's 1am. I did a lot of math to solve the cages in box 6, probably more than was intended, and that pretty much gave me all the digits in box 9. I remember that at least.

[@christophstahl8169]

.. for Alexa the same reason ... 🤣