How NOT To Cheat At Sudoku!

[@fynnsternis6432]

"Tatooine Sunset", also known as "We're nowhere near getting a digit" and "We need another swordfish"

[@darreljones8645]

I would've named it "Tatooine Swordfish".

[@condor1234]

no no no no no

[@andremouss2536]

The empire didn't catch R2D2 there. But where is that cell ? Row two, diagonal two ? Neither they catch C3PO, that wold be column 3, parity Odd ?

[@TheEricthefruitbat]

The best thing about this puzzle is the swordfish for a digit that does NOT appear anywhere in the grid, IMMEDIATELY followed by an x-wing ON THAT SAME MISSING DIGIT.

[@sebrofniloc]

Interesting definition of 'best' that you are using there! 😉

[@Tiger21us]

That is indeed awesome. And mind boggling~ :0

[@susanne5803]

Now I'm officially scared ...

[@christophejefferies522]

@@inlumina_punctro You can click the link in the video description

[@addicted2222]

Absolutely agree. This is incredible. The most beautiful and brutal classic sudoku I've seen.

[@Thedamped]

This is the only channel on KZbin that feuds with itself.

[@mydemon]

"Watch me one-up that bastard!" ;)

[@coreyyotto]

I admire the absolute restraint to require just one x-wing to solve a Star Wars themed sudoku.

[@matttondr9282]

But it’s an x wing on a digit not even present in the grid, located by a swordfish again on that same missing digit.. Wonderful! The one x-wing that truly counts 👍

[@inlumina_punctro]

Can someone indicate where is the PC software which allows you to use colors and numbers in different position? Is a pdf, or? I mean for PC, not for mobile. Thank you! Is it free, it costs?

[@Mrkirkulator]

@@inlumina_punctro its the CtC website/app - all the videos have a link to the puzzle in the description

[@glum_hippo]

I am perfectly serious when I say: MORE videos like this please. This is a very nice contrast to your usual and equally wonderful videos. If I may suggest: make your show 95% live solves as usual and maybe 1 in 20 can be 'walkthroughs' like this one. Though I trust your instincts more than mine of course.

[@zelassin]

Well there’s a reason why this was supposed to be a patreon video. The goods go there

[@ardemus]

@@zelassin That really would be too bad. I was an early Subbable member, and got transferred to Patreon when they merged. I was there for a few years before they slammed my account with a series of unexpected charges. Customer service was far beyond bad. IIRC, I was using a side account with a low balance so they repeatedly over-drafted it, I wound up getting the bank to wave the fees because they were unauthorized charges, had to get refunds from the individual creators directly, closed my account, and swore off the company. The several scandals they've had since only confirmed my opinion of the company. Patreon simply isn't an option for me.

[@AFastidiousCuber]

All told, I think this is the fourth time this puzzle has been mentioned and the second time it's been solved on this channel. That's pretty impressive for a classic Sudoku!

[@r0bw00d]

Close. It's the third time, to my awareness.

[@stephenbeck7222]

r0bw00d Simon first mentioned he couldn’t do it but posted a link for others to try. Then Mark did it with bifurcation. Then yesterday I think Simon said he wanted to show the logical solve. And today is the solve.

[@r0bw00d]

@@stephenbeck7222 Hm. Simon mentioning it must have been in a video that I haven't seen. I only participate in the classic solves.

[@stephenbeck7222]

Looking back, Simon actually mentioned it twice before Mark’s bifurcation video. In ‘Top techniques for classic sudoku’ (Rimu’s classic), Simon showed this Tattoine puzzle on screen and said he couldn’t finish it. In the ‘Greatest puzzle arg ever’ (killer sudoku from DiMono) he updated that he had found the logical path that had taken him forever.

[@AquaShibby3000]

@@r0bw00d Oh, really? Just curious why that is.

[@negar1368]

No no noooo we are nowhere near getting a digit! This is so much fun to watch

[@c0d3_m0nk3y]

I enjoyed this so much, I wish you could like it more than once!

[@masheroz]

@@c0d3_m0nk3y you can like it an odd number of times.

[@moji8225]

@@masheroz but does that give us a digit ?!

[@masheroz]

@@moji8225 depends, did you colour it orange or blue?

[@moji8225]

@@masheroz oh my god, i knew i messed up somewhere, it was all about the colors (´･_･`)

[@pardox28]

This puzzle finally got me to understand swordfishes!

[@benharkness8152]

Yes same

[@jonathangreene682]

Same, I finally get them now and also how they similarly relate to jellyfish. X Wing -> Swordfish -> Jellyfish. Is there a 5x5 one also? Maybe haha.

[@80SPIce]

Yes, me too :-) I tried the Tatooine Sunrise now for myself with what I learned from this video. Took me about 3,5h and I‘m all dizzy 😵‍💫 And I understand now why Simon so often seems to not see even the easiest numbers to get rid of by e.g. Sudoku. It becomes really hard to see those things when the brain runs at >90% for a longer time. But I‘m proud I could solve it myself, as it even included 4x4-swordfishes - at least the way I solved it. Thanks @Simon for your videos and your good explanations 🙏👍

[@antalbojtos4413]

"I was never prepared to bifurcate, so I never got anywhere" My heart melted for you, Simon. If you were a world-class solver, this channel might not exist, and that would be a huge loss for everyone. I thank you for not bifurcating.

[@victorfinberg8595]

But Simon IS a world class solver. There's more to life than winning competitions, and there's far more to being great than competing in competitions.

[@libbilation]

This is an all-time great CTC. Up there with the original Miracle Sudoku. Classic Simon turning sudoku-solving into an absolute thriller - though in this case more of a detective story! So completely wonderful

[@ArloLipof]

When in a classic Sudoku puzzle, you hear: ‘that gives us a bit of a Sudoku relationship’ after 33:53 (!), you know there is a true genius at work. The sheer elegance of Simon’s logical reasoning here is simply magnificent.

[@philipnewmansudoku]

An easier way (IMO) to think about the swordfish at the start of this puzzle - and in fact, this is what the puzzle was built around - is to think about the geometry of the givens. Considering the "most useless" 5, for example, you'll notice that the columns (349) Simon picks out for the swordfish all have givens in the same three rows (257). Since the given 5s are on three *different* rows (348), the 5s in columns 349 must be in the remaining three rows (169). In fact, there are two such "3x3" patterns in the givens, offset from one another, and this is what leads to all the swordfish at the start. (The 279 swordfish are so fruitful because of the high degree of overlap - eight of the nine givens are found in one of the 3x3s.) It's important as well that all of the givens not part of those 3x3 patterns (all in row 9) are also offset from both - this contributes to the 2 and 6 swordfish at the start. "One of the most useless swordfishes" - In fact, you can solve it without using the 5 and 6 swordfishes at all. (There's a 3 swordfish at the end to find instead.) You can also use a jellyfish for the 1s rather than the swordfish/x-wing combo, but the x-wing around the sun is so pretty.

[@philipnewmansudoku]

And it's worth noting that Tatooine Sunrise is actually a tad easier by the metric of Andrew's solver, though whether it's actually easier is debatable. ;)

[@negar1368]

Thank you Philip for this amazing puzzle. The symmetry was how I approached it and I should say the solve was much more elegant.

[@philipnewmansudoku]

@@negar1368 You're welcome, and thank you to everyone for the positive responses! I obviously thought the puzzle was good or I wouldn't have submitted it, but I'm stunned by the attention it has gotten the past few days. :)

[@yigityargic2814]

@@philipnewmansudoku You are a legend for creating this legendary puzzle. Well done!

[@isakoolsson]

I noticed that pattern when Simon made the first swordfish, because it made a second swordfish of 5s

[@tillwiemer757]

29:00 after going through multiple swordfishes he explains the X-Wing to wipe our tears away

[@hauntedmasc]

I mean... I rather enjoyed Mark's bifurcation solve, but this... this is truly extraordinary.

[@HalfBakedLunatic]

Yeah - stunningly good for both of them. Even with the bifurcation, the fact that Mark did it as quickly as he did was amazing - but this just blew my socks off.

[@hom-sha-bom]

And extremely unnecessary

[@andrewg2032]

True, bifurcation just means your guessing.

[@ArunIyerS]

I am glad (and amazed) that Simon persevered through this puzzle and created the video. I cant even imagine how Philip might have even thought of designing such a puzzle. Incredible!

[@miniwizard]

It would hardly be a true Tatooine Sunset without an X-wing hidden within the horizon to save the day.

[@carlosrodriguezb]

That was amazing. It was straight forward from the X Wing

[@MrCharlieArgo]

Gotta love the principles on my guy. Refuses to bifurcate knowing that means he will never become a world-class speed solver. Too much respect for the puzzle and the solver. Gotta love it

[@thejeqff]

That was so incredibly satisfying. Thanks for doing the logical solution path. I found the swordfish on 7s first, but couldn't find the others. Your method for finding swordfish patterns may make this one of the most helpful videos in the entire CTC catalog. Really fun to watch.

[@jddevos1]

Thank you for walking through this solve. I am trying to learn these advanced Sudoku techniques, and videos like this one really help me out. I paused every time you highlighted the swordfish possibilities to try and find them myself, and I cannot explain how satisfying it was when you confirmed them. Is there any possibility for a series on these techniques? Specifically, I really struggle with hidden pairs/triples/quadruples. Thanks again for the wonderful video.

[@brandonsurowiec8789]

Gave me tons of swordfish practice too. I now understand them sooo much better! Was super helpful.

[@majascha3414]

32:29 Simon: "I'm trying to work out what the next digit was. There are some cells here that are more resticted than you think." Me, realizing the cell he is hovering over (r4c4) is a naked single 6: Haha! For once I know what he'll do next! Simon: Oh, over there! That cell can only be 3 or 4! Naked single 6: remains unsolved for another 5 minutes, gets solved because there is no other place in the box for it

[@Jackleber]

Yeah! I just said the same thing!

[@mindbreaker194]

Wow, even Simon made a slight mistake in the 2's swordfish (15:00), but he luckily selected the right columns. That says a lot about how hard this evil monstruosity is.

[@rosebuster]

Yes, Simon. This way of solving is far more satisfying. Because it allows to appreciate the surprising beauty of this puzzle's construction. While Mark's solve doesn't make it possible to see any of that.

[@ceevio_art]

Very true, but Mark would progress to the next round in a competition, which I think was the point he was making in his deliberate bifurcation "if-then" solve.

[@snakeyesz]

THAT WAS INCREDILBE! SIMON TO WATCH YOU LOGICALLY SOLVE THIS AND ALSO IM REALLY GRATEFUL FOR YOU EXAPLAINING THE DIFFERENT TECHNIQUES

[@tyrgannusgaming6657]

This is easily the hardest Classic I've ever seen

[@Wecoc1]

There are many that are way harder than this, but when they're that hard it loses quite the fun in my opinion. On Andrew's Stuart webpage (shown on the start of the video) there's a section called Weekly Unsolvable that not even the solver can solve.

[@philipnewmansudoku]

@@Wecoc1 Since you mentioned the "unsolveables", I'll point out that the pattern this puzzle is based on, with the 3x3 givens, is quite fruitful in terms of finding hard puzzles. Before I went on a fishing expedition, I found quite a few in that vein.

[@kellymiller7986]

@@philipnewmansudoku This puzzle is very hard, but it is also very beautiful. Thank you for making such an evil, wonderful, fair puzzle.

[@andremouss2536]

The converse applies : this is hardly lthe easiest Classic (lol)

[@mrmonster3434]

A puzzle worthy of M. Hercule Poirot himself. And to solve it, we must use "ze little grey cells"!

[@BozoTheBear]

exactly what i was thinking! :)

[@akhos9876]

Yes. Just yes.

[@CootBusiness]

That's weird because I've been listening to the Poirot theme while solving Sudoku puzzles. Is there some connection between the two?

[@matttondr9282]

Nice one 😂

[@SonicGamesPlayer]

I've never thought that a classic sudoku can have such a beautiful logic!

[@diegobolso2005]

Just the fact that he never said "now we are cooking with gas" is enough to understand how diabolical this piece of art is.

[@vetman98]

Thank you for explaining the logic.

[@Ruddigore]

10 out of 10 for this absolutely superb solve but I'm afraid you came in last place in the competition in which this Sudoku featured. So glad you decided to broadcast this solve for us.👍

[@ringoderbar1522]

I got 4 swordfishes in 40 minutes, without knowing the concept of the swordfish. I see this as an absolute win!

[@grenvillephillips6998]

The thought of doing reverse notation is mind-bending.

[@rickrice8660]

Agreed ... and I don't get why he does that. I thought he said, at the finding of the pattern in columns 3, 4 and 9, that the 5s could only go in those two blue cells. So why not use center pencil marks for those 5s and corner marks for all the other possibles 5s in the other columns (or vice versa). Maybe it makes more sense as we progress ...

[@asherhiggins2018]

@@rickrice8660 It seems he has a sort of moral code where penciling in that way is considered wrong.

[@andrew.pendleton]

Interesting choice with the alternate notation. When I solved this when it was first posted, I ended up just doing center notation for all the possibilities for every cell, and then whittling away digits as I found swordfish, which worked fine but obviously took a little while (I think over two hours in total for me).

[@sunriselg]

That notation is what I did as well (and what I often do with more complicated puzzles). This helped a lot with with the end. In my first solve it took me only 7 minutes to go from one digit to solved.

[@willemkossen]

Could add red pencilmarks to the software for this reason ;)

[@ragnkja]

Willem Kossen That would be nice.

[@GauravBafana]

The greatest thing is even with new software where simon can just double click a colored cell to remove the shading from all colored cells but he still does it manually and ends up finishing in an astonishing time while making it interesting. Really great work. Loved the puzzle

[@kduhy4379]

Have been following this channel for some time and have learnt a lot from you two, however, this puzzle and the different ways that you solved it has been fascinating. Thank you

[@Waggles1123]

It feels like you guys need to include a negative pencil mark (maybe red?) in your software update. It'd be nice to note that a cell could be a 3, but it can't be an 8.

[@JohnJillky]

This, and more colors would be great, but I can understand if they want to keep keyboard number shortkeys connected to all of them (tho, I feel there could still be 2 more colors + make white just the delete/backspace)

[@nendwr]

Maybe that's what the B key is for.

[@FirstLast-gw5mg]

I found Simon's "negative pencil marks" very confusing and opted to just fill in all *possible* pencil marks instead. I was still able to follow along well enough and it basically put me on track to filling in all possible digits as he suggested, so I just went ahead and checked for swordfish on the remaining digits, found several that helped narrow it down further, and it solved from there. Then the only confusing bit was to remember that now corner pencil marks were actually all possible digits, so they were actually like center pencil marks at that point.

[@omkelderman]

YES! ive had multiple times on completely unrelated puzzles that I felt the need to mark a cell in some sort of way to signal to myself that it cant contain a certain digit

[@michaelpeele5739]

@@FirstLast-gw5mg After a few "obvious" numbers, I find myself just putting all of 1-9 in every cell and removing them. I also will see some x-wing, and I'm learning swordfish.

[@marcohanig176]

It didn't affect the solve, but I believe that at 14:41 you incorrectly colored a 2 in box 2-3. Same for coloring the 6's in column 6 at 15:56

[@rogerstone3068]

Yes: I saw the possible 6s mis-identified in the central box, and I was waiting all the way through the video for that to come back and bite him... but it didn't.

[@marcohanig176]

@@rogerstone3068 Finally realized that for a swordfish, the only marks that matter are the ones in the swordfish columns.

[@bloodclaat]

I saw that too.

[@PKAdazGalaxiaz]

is it solvable via swordfish if he didnt mistakenly color that box? I'm trying to understand how he would have used swordfish if he hadn't colored that 2. started learning 2 hours ago so there is lots I don't understand yet.

[@Reign14forever]

Oh the shade of it all the drama of it all im LIVING for it

[@melodywawichi802]

30:46 for digit #1 i swear we need a top 10 list of the puzzles with the longest amount of time taken just to place a digit down

[@zoltankalovics7910]

actually at around 23:20, when he did the swordfish with the 8s, that lead to only 8 possible position for 8 in row 5, so even though he didn't put it in, it was already placeable nvm, seems like he missed one possible position on for it in r5c6 when he colored them in, so it could also go there, if I see it correctly

[@sunriselg]

In my first try of the puzzle it took me 55 minutes to place the first digit, then 7 to place the rest.

[@nilsp9426]

Let's call it: "First blood" as a hommage to the gaming world ;-)

[@zelassin]

Don’t forget this is not Simon’s first solve of this. Original time to place a digit could be much higher

[@nishanthn4927]

This is legendary solving!!

[@bjornek2]

As someone already said, it is always extra value in videos where you explain in detail like this. Very educational, Simon. Thank you, Simon.

[@Mindseas]

This solve was absolutely stunning, stellar work and crystal clear explanation! Thank you Simon!

[@MarkTillotson]

double stellar in fact :)

[@Derekloffin]

Wait, you already solved this and it still is a 39 minute video?! Well, no wonder I couldn't even make a dent!

[@arturodeloz]

Wow! It was a joy to follow along with you on this journey to a Galaxy Far Far Away.

[@bartw8523]

Wow what a great solve. Unbelievable that with all the techniques you can solve this sudoku. And that reminds me that someone who has made this must also be brilliant to see all the techniques behind this super great sudoku. I loved how Simon solved this puzzle. It was a pleasure to watch.👍🏻👍🏻👍🏻👍🏻👍🏻

[@mbash7887]

Thank you ​ @Philip Newman for making this puzzle. Thank you Mark for showing us the "easy" way to do this puzzle. Thank you Simon for showing us the "right" way to do this puzzle. This is the coolest puzzle I've seen on this channel so far. "Wut a puzzle!"

[@jonbrowne8334]

That is the greatest solve I have ever witnessed! Wow oh wow! I could follow to a point but it was very difficult! To all those people who have solved this puzzle I bow before you! This is beyond my current capability but I will keep o trying to master these puzzles! An unbelievable video Simon!

[@alvaropallete]

Thank you very much Simon, I could find the swordfish for 2, 5, 7 and 9, but not for 6, much less for 8, much much less for 1, and much much much less find the naked single at 30:45. I just suggest doing the shading by boxes rather than by columns or rows, it's easier to visualize and avoid mistakes (i.e. at 22:12 r6c6 is not shaded so that could lead to a swordfish with columns 5, 6 and 8, that would crash our puzzle later on). I bet this will remain as one of the flagship videos of the channel. I'm not only giving a like to it, but also saving it in my library 😁

[@triplea657aaa]

I always love how you never resort to bifurcation and always go the logical route. Never change, Simon!

[@ReactionVideoDotAvi]

I've been watching your channel for a couple of weeks now and I'd like to thank you for explaining in simple terms how the swordfish pattern works, all the guides I've read while trying to up my Sudoku game have been far too complicated for me to grasp the logic and I finally got it with this video. Thanks Simon.

[@J4ckyCh4n]

I normally don't comment on videos, nor thumbs up them, but I give this solve a 10/10 standing ovation

[@Bobbieness]

I am his wife and sat next to him during this solve. Can confirm standing ovation happened, followed by “I need to get my phone to thumbs up this video.” (We watched it on the KZbin app on our TV.)

[@gavinmcclenaghan7787]

Yes, this is a satisfying solve. But I have to say this also gives me an equally great appreciation of Mark’s solve. The elegance of pure logic vs. the efficient and judicious application of brute force. More of these style comparisons please!

[@Eftelingannie]

I love seeing you solve it this way. What a great puzzle to solve it logically. Truly loved it.

[@yigityargic2814]

When I got this puzzle, I pencil-marked literally every cell with all digits from 1 to 9 and went by elimination. In fact, I started doing this with every classic sudoku now. Although I had the clue that there are lots of swordfishes, I still missed the swordfish with 1s, because I was truly not expecting it.

[@sunriselg]

I also use that notation for most puzzles. For this puzzle that made the last bit a lot faster.

[@littleschnitzel8226]

I have bad memories about this puzzle, this is the one I almost solved after more than one hour, missing only a few last digits, but no, accidentaly restarted it instead. I'm still furious about it, I tell you. :)

[@r0bw00d]

You're going to have shell shock because of this puzzle.

[@QuantumAnswer]

THIS PUZZLE IS UNBELIEVABLE!! I've noticed an "amazing" thing... once you put 4s in (r6c7 and r5c1) there is yet another swordfish on 4s! This restricts r1c6 (Simon puts there only possibilities to be 3 or 4 - Nope :) it's 3) and immediately after that placed 3 there is another swordfish on 3s... restricts only two cells in the grid, but once you've seen so many, you are looking for more.. - and they are THERE! Well... "I accolade by a sword Sir Philip Newman as main fisherman..." ;-) Simply amazing..

[@sunriselg]

First solve too me about 62 minutes (I knew I had to look for swordfishes), second solve was 21 minutes. Spoilers for the tightest solving path I found: 1. Swordfishes on 2, 5, 6, 7, 9, 2. 279-Triples and pairs 3. Swordfish on 8 4. 145 Triple in row 9 5. Swordfish on 1 6. X-Wing on 1 7. Place first digit 8. Solve the rest

[@jerryknox4841]

Finally, I understand what the use of colors is for. Years ago I downloaded a Sudoku app and it had colors, I did not know what to do with them and everything was so confusing, I deleted it. Thanks so much for letting me understand what they are for, I truly appreciate it. Oh, and great job on solving that puzzle.

[@BinaryArmorOnline]

This is actually a super cool style of video. I would love to see more videos where you're going through a sudoku for the second time and pointing out what exactly it is you're looking for when you're scanning the grid and how to notice it.

[@briancjones58]

What a fantastic classic sudoku! I have saved this to keep my swordfish skills fresh. BTW - I found a 2 X wing Pattern early in the game that only later aligned with the greyed out cells that identified restrictions. I also tried a swordfish on the 4's that I errored in box 6. That set me back until I saw the 1 X wing pattern later in columns 1 & 6 at rows 1 & 6. Just when we thnk that classic sudoku readily manageable we are gifted this! I know that this is a 3yrs ago vidoeo....but trust me. Play this once a month and you will still get stumped. Thank you for this Phillip Newman!

[@fresnik]

At 14:40 Simon marks R6C8 as a possibility for a 2, when there is a 2 in the grid and uses that as part of the swordfish!

[@TheSebmab]

Yes I find it disturbing too... Does that mean that this swordfish should not apply ? In that case, does that mean, that his demonstration is just lucky ?

[@vilsbol]

This - along with Mark's video from the other day on the same puzzle - has to be my favorite video of yours so far. I really enjoyed it, thank you both!

[@eleirbag9937]

What a lovely sudoku - and what a smart way of solving it ... I really loved it! Only waiting for Simon to discover the 79 pair (and consecutive 56 and 18 pairs) in box 6 made me kind of nervous /excited ... Maybe this could've shorten the path a tiny little bit (?). Really fascinating puzzle; wishing to see more of this kind! I haven't been able to solve this sudoku on my own - but I tried hard even including looking out for those helpfull patterns. In the end I "gave up" because I sort of lost the overview. All the more I had been looking forward to watch Simon-solving-without-using-"what-if"s ;-) Thanks a lot!

[@bingewatcher391]

OMG!! I've become a Sudoku addict because of this channel. I had to try this puzzle before seeing it on the video. Just finished it!! Took me 4 hours 58 minutes and 55 seconds!!! Didn't get the first number until like the last half hour. My first number was a 4!!! Great channel!!

[@bingewatcher391]

Hahaha!!! Yeah I was also going to say that I had a hard time finding Swordfishes and x-wings before this puzzle. Now I think I'm almost an expert at it. hahahaha

[@girlindigo8]

I love that Mark and Simon have different solving styles.

[@epeo22]

This, coupled with Mark's video, is THE best video that Simon could have ever done to convince me that bifurcation is indeed absolutely necessary. I think that doing all this work makes sense when filming a video on youtube, but it's not fun at all, and in competition it's just absurd. Don't mistake me, I loved the video, it's fascinating, but I don't want ever in my life to do something like this by my own.

[@VanpyroGaming0]

Is this the one where Mark had to double bifurcate to solve it?

[@TheGerkuman]

Yep. Right on camera too. Was surprised it wasn't flagged as unsuitable for monetisation.

[@OttoBittoSplatoon]

Well, bifurcation was the point of Mark's video: he didn't even try to solve it logically, he just showed what he would have done in a competition to finish it more quickly

[@vasilybulochkin4622]

Do you have link for that?

[@Luckingsworth]

@@vasilybulochkin4622 litteralt yesterday's episode. Titled "how to cheat at Sudoku"

[@vasilybulochkin4622]

@@Luckingsworth k thanks! I've missed that episode

[@MathieuC321]

Might be the 4th or 5th time I watch this video, yet 1 year later I had to come back and watch it again… it still amaze me how clever this resolution is. I love the logic in it !

[@MathieuC321]

And again 😄

[@MathieuC321]

And again !!!

[@JohnRandomness105]

Bifurcation at 1:20 -- then you'd probably detest me. On the other hand, at 1:40 ... Around 8:00 -- swordfishes of 5s: I found a different, vertical (or rotated 90 degrees) swordfish of 5s that eliminated everything Simon's swordfish eliminated. Around 39:00 -- "No-no-no, we're nowhere near getting a digit." Earlier, with the focus on 789, I paused and returned to see what I could do with them. I could place pretty much all sevens, twos, and nines starting with a three-row-three-column triple.

[@wanderlustwarrior]

"The hardest naked single you will ever see!" Well at least he wasn't up in your face with it!

[@DavidVanmeterDutch]

Didnt know I could get that excited watching a Sudoku before. When he got the first digit, the 4, I shouted out and jumped up! Was a marvelous puzzle. Now, I learned swordfish and x-wing! So great!!

[@leagilbertson8920]

This was amazing! And I finally understand the swordfish! Thank you!

[@JohnRandomness105]

I did this puzzle again today watching Mark's solve. I didn't *completely* forget my attempt at this puzzle four months ago. I recalled one comment earlier about placing -- I read it now, 7s, 2s, and 9s. I found four swordfish -- 5s, 7s, 8s, 9s. I think I found a useless swordfish of 2s. Then I had to bifurcate. I'll try again now, and see what I can do in my third solve. (Later) Maybe not in 8s. (Later still) The swordfish was in 6s, not 8s -- 5s, 6s, 7s, 9s. A 2 swordfish turned out useful. (Applying it revealed a 2nd swordfish pattern in 2s that did nothing.) 6:30 Simon mentions five swordfish. Were they 2, 5, 6, 7, 9? I shall see. I'm stuck, even after finding them. 6:50 Actually, I did find the swordfish without coloring earlier today. This round, though, I found coloring in cells a number could NOT reach helpful. 12:00 I still maintain that it's easier to color in cells a digit CAN'T reach. At least it's less stressful on the brain. 15:20 This is probably just an interesting factoid, but once the swordfish in 2s eliminates cells, one gets a 2nd swordfish in 2s in columns 1, 4, and 6. 28:20 The X-wing in 1s got me my first digit, along with my second, third, fourth, etc. digits. In fact, it finally cracked open the entire puzzle. I don't recall what I did or claimed to do four months ago. PS: In the process, I saw Mark's bifurcated 5 in the other video properly ruled out. 30:50 I already had the cell penciled as 14 before the X-wing, so I immediately got that 4. 31:10 Once in a while, it is advantageous to over-pencil-mark. In this case, once a digit got swordfished, I penciled in every cell that could still contain that digit -- even penciling a digit into four cells in a block. Once I got the 4, I placed and penciled 4s through the grid. Consequently, except for 3s, if a cell didn't have the digit penciled in, that digit wasn't there. That made it straightforward to finish to the end of the puzzle. 33:20 Um, what?! "... but we're not using a computer."

[@JohnSmith-rf1tx]

Well, I had totally failed on my initial try at Tatooine Sunset when it was first mentioned in the previous video. But after watching this video, I gave Tatooine Sunrise a try and managed to finish it correctly in 1:28:00 using the same techniques shown in the video.

[@mtadd]

At 14:59, you can also exclude the 2's using the swordfish on rows 3,4, and 6. I'm really grateful that Simon is taking the time to explain using the technique with this sudoku. I'm finally beginning to understand how to use the swordfish technique properly.

[@sunriselg]

Every fish has a perpendicular fish. Resolving the horizontal swordfish has the same result as resolving the vertical one.

[@GlenaGarrett]

I'm not logical by nature and started Sudoku late in life. For me, it's always a marathon on difficult puzzles. Swordfish are incredibly difficult for me to recognize but your approach to this puzzle clarified them much better than any of the explanations on simpler puzzles I've seen. My goal is to gain logic skill, since I know for certain I will never be fast at these things.

[@Da6moose6]

Simonism watch: BOBBINS: 0 :( Calling something useless: 1 Cooking with gas: 0 :(

[@francoisduez601]

It's different when it's not a live solving 😉

[@Da6moose6]

François Duez I agree lol. I enjoy watching Simon become frustrated.

[@Nighthound]

It took so long to cook Simon ran out of gas: 1 :(

[@meepmeepinton]

you forgot "Well that's absolutely useless!" When spending a while figuring out a digit and also "What is this cell? Well it doesn't matter"

[@RatKillCat]

Simonisms-I love it! The list can be expanded upon, especially in regards to the numerous variations of compliments Simon tends to give to certain creators and their puzzles (“gorgeous”, “brilliant”, “beautiful”, etc., oftentimes preceded by “absolutely” and occasionally followed by “piece of logic”). Adding those to the list could however make Simonism drinking games hazardous when it comes to the miracle sudoku videos. Funnily, Simon saying “bobbins” a lot has somehow slipped past me. As per the Baader-Meinhof phenomenon, I will probably start hearing it a lot from now on.

[@jimjimellell]

I finally finished it correctly after 2 weeks and 3 failures. I did not use any swordfishes or x-wings, only Ariadne's thread and the "slot machine" technique (which I have been using for years but didn't know that it actually had a name).I liken solving this puzzle to chopping down a tree with a pen knife, simply chasing down 1 thread after another until I could eliminate 1 candidate after another. I also finished the companion puzzle Tatooine Sunrise and that seemed a little easier (only 2 days!) I hope you post a video on that one too. I also hope to see more puzzles by Mr. Newman. Brilliant!

[@tarotcomPauloEvoLua]

I’m very thankful for this marvelous class you’ve showed us !!!

[@patrickhazlehurst8472]

You are a brilliant explainer of the logic Simon. Thank you .

[@vantrickpaughney3830]

Not gonna pretend I would've been able to solve this by myself in any way, BUT! I think Simon could've placed his first digit a bit earlier. When he performes the swordfish trick on digit 8 at 22:07, he takes into account only rows 1, 4 and 8 to highlight a triplet. But if you take into account row 6 as well, it would form a quadruple tie between columns 1, 3, 7 and 9! And you can see, within that restricted tie digit 8 can only fall into row 6 along the first column! So, that's the first digit - 8 in C1 R6. (from which you can also derive the fact that digit 8 falls into C3 R8)

[@pietndala7394]

Absolutely stunning creation and limits of reason... wow ... I’m super impressed...

[@Tiger21us]

I loved watching this, I may actually understand the swordfish now. More video like this one would be nice :3

[@sinajakelic]

I keep coming back to this one. This must be the most impressive classic sudoku ever. ❤ thanks for a fantastic explanation.

[@Azayaa42]

Holy moly this was seriously impressing and sooooo good to watch!

[@cycladianpirate]

Marvellous!!! Simon has used the epithet "By Sudoku" in a Classic Sudoku puzzle. CTC breaking new ground again!!!

[@emilywilliams3237]

Another in my tour of past puzzles; KZbin was so kind as to suggest this to me right after I watched Mark's bifurcation method on this same puzzle. Here is what I learned: 1. I do not mind bifurcation as much as Simon does. 2. I never fully understood how to spot swordfishes - I understand what they do, how they make things happen, but was not sure just how to see them, but seeing them is it six times in this puzzle I now think I get it. (Though at one point Simon says, "pause the video and see if you can spot the next one" and I confidently said out loud what I thought it was, and of course I was totally not correct ...) 3. I do understand the appeal of the strictly logical solve of a difficult puzzle like this one. I am sure it must be very satisfying to be able to know for a certainty that it is truly logically provable to have a unique solution. On that score, well done, Simon. And 4. 9 months ago, when I first encountered this channel, I could do almost none of the logic involved in difficult sudoku puzzles, really hardly even the basic stuff. And now I really get it and can spot x-wings and use them, I get some of the other things in the "tough" list in that software that Simon showed at the beginning. And I also understand and can make use of many of the geometric and maths principles that have been taught and illustrated on this channel by Simon and Mark. Wow, what a journey - and this puzzle proves that I am not anywhere near the destination, but I am happy to keep going. Thanks so much for all that this channel has been and is, Mark and Simon.

[@Martykun36]

On 22:12 there is another swordfish on the 8s in columns 5, 6 and 8. This eliminates two positions for the 8 in column 1, so Simon was much closer to getting a digit than he thought :)

[@quentind1924]

I thought i was the only one to found it !

[@Deuxice]

this is just absolutely beautiful. not even the word beautiful can do justice to how beautiful this puzzle is.

[@Felixkeeg]

This should be called 'high sea fishing' with all the swordfishes one has to catch

[@PascalVERGNEAU]

At 22:43, there is a 2nd simultaneous swordfish on 8's with columns 5,6,8. Two swordfishes means 6x6 col/rows are locked. On a sub 7x7 grid for the 8's ==> there is only one possibility for the remaining 8 that is in fact the first digit that we can write in this grid (c1r6)

[@MatthewBouyack]

Re-watching this almost two years later. Such a classic!

[@kelperdude]

Cool. I've been waiting for this. I do okay on the standard ones, but this one was a beast to try.

[@marcoe3676]

I by no means could of got this far but i did notice during your 8’s swordfish there was actually 2 swordfishes on 8’s which immediately gives you the 8 in column 1. Which also happened to be at the time you said we were no where near putting a digit in yet. Other swordfish is column 5,6 & 8

[@RedPandaLesbian]

I immediately paused the video and came to the comments to see if anyone spotted that second 8 swordfish, glad I wasn't going mad!

[@RichSmith77]

As the constructor himself (Philip Newman) has commented elsewhere, there isn't, in fact, another swordfish in columns 5, 6 and 8. Simon missed shading in r6c6, which could also be an 8.

[@RedPandaLesbian]

Ahhh that makes sense too, thanks for clarifying!

[@julieenslow5915]

OK now we have Trouble. Mark - you called this "one of the hardest puzzles you will EVER see." You know of course, that now your best puzzle constructors are all going to be shooting for that statement. Or to best that statement. Because now Phillip Newman has a puzzle at the top of all lists - that means he has no where to go but to BEAT this one. So this level complexity is the goal! Well I for one will enjoy watching you and Mark do them all, I'm not up to those yet! Hugs for this solve - it was inspiring!

[@ragnkja]

I’ve tried the Tatooine Sunrise sudoku as well, and in my opinion it’s even harder.

[@rebeccanorth6349]

Truly stunning solve! Everyone will have to up their game to match you now Simon...A*🤙

[@saittou]

who would believe that in such a desert planet you would find so many fishes

[@lylecampbell8288]

After you taught me what a swordfish is, I found that, for each of the 5, 7 and 9 swordfishes, that they were actually double swordfishes. Once I'd coloured all the possible places for the digit, located the swordfish and recoloured those 6 digits, I then whited out the other, now impossible digits in those 3 rows and columns. This left 6 remaining coloured digits which formed a second swordfish in the remaining three rows and columns. This leaves you with 2 possible digits in each of the boxes not already filled, formed from the two swordfishes, and this gave exactly two distinct ways to fill in all those digits. So, I ended up colouring and putting in corner markings for digit possibilities. The colours ended up pretty chaotic but the corner markings kept me on course and let me recolour for each new swordfish. I found that the 7s and 9s overlapped, with 7-9 pairs in the three boxes without an initial 7 or 9 but the 5's didn't overlap at all with either of them. All this meant that as soon as a single digit was put into any of those cells all the 7s, 9s and 5s unravelled at once. Of course, that didn't happen until much later... This also worked to lesser degree with the other swordfishes. There was always a second one, but I found they gave less and less information. I still had to follow my way through the whole school of swordfishes. The only real advantage was a much reduced number of possibilities to sort through each time. The second 8 swordfish left me with a single 8 in box 7 but I still only got to fill in half the 8s from that and it didn't break open the 7s, 9s and 5s.

[@neilramsey1368]

After watching your expert explanation on swordfish and x wings I have a new appreciation of how to spot these solving techniques- Thank you

[@richardrule494]

Easily the most impressive solve I have ever seen. Thanks

[@Grikkez]

Tatooine Sunrise is also a quite nice puzzle. The solving technique is similar, but the puzzle as a whole is a bit easier. Took me about twenty minutes.

[@honigschlecker1]

Woah, that's fast. I found six swordfishes and was pretty happy to solve it. Took me I think 40 minutes.