Diabolical Sudoku Masterclass: This IS Genius

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Hi! We're Simon Anthony and Mark Goodliffe, two of the UK's most enthusiastic puzzle solvers. We have both represented the UK at the World Sudoku Championships and the World Puzzle Championships. We're also "cryptic crossword" aficionados. Mark is the twelve-time winner of The Times championship and Simon is the former record holder for most consecutive correct solutions to The Listener crossword. We hope we can help your puzzle solving while also introducing you to some of the world's best puzzles.
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[@no-feetmcgee5577]

An hour and a half in, I had 8 digits in the grid and every other cell fully pencilmarked, after spotting *two* X-wings, which I was already proud of. I must admit, I was starting to feel the temptation to bifurcate; and even worse, I had spotted two places where I could exploit uniqueness. But then, when all hope seemed lost, a shining swordfish appeared before my eyes to save the day. The puzzle collapsed before me, and I triumphantly entered the last digit at 1:33:19, without ever resorting to uniqueness or bifurcation. I felt like a sudoku master. Riding high on my success, I went to watch the video... to see that Simon discovered both X-wings and the swordfish almost immediately, within ten minutes. Well, I must bow to the true master. But this student is still learning, so you better watch your back. ;)

[@sonalita_]

I don't understand why people think resorting to uniqueness is bad. It' is still using logic based on the fact that each puzzle must have a unique solution, so why not use that fact to make those logical deductions? I see nothing bad in doing so.

[@no-feetmcgee5577]

@@sonalita_ I guess that it feels wrong to me because, almost by definition, uniqueness arguments are almost never the "intended" solution path. The creator *must* be able to prove their puzzle has a unique solution *without* presupposing that uniqueness, and thus I as the player know that I *should* also be able to find logic that doesn't presuppose uniqueness. That said, I do enjoy puzzles where Girth's theorem is the key, and that also relies on uniqueness.... so perhaps I'm a hypocrite. I just go based on what "feels" good to me. :P

[@johncolt3582]

part of me wonders how you describe the experience of having your first child or something, when you praise Sudokus like this

[@bobstreet2491]

WHAT a baby! This is the most beautiful -- beautiful -- baby I've seen this week. Absolutely stunning.

[@KurtHugoSchneider]

I really don't mean to spoil the beauty of this puzzle, bc the solution was so so extremely nice, however just want to point out that the puzzle can be solved very quickly with uniqueness. after putting a 3 in c4r3, you can also instantly place a 5 in c6r7. why? if not then c3/7r7 would both be a 35 double and the puzzle couldn't have a unique solution. after this the rest of the puzzle fell apart quickly. no advanced techniques did the puzzle in 10:12, and sadly i didn't appreciate any of this beautiful construction until watching your solution afterwards.

[@Julesoby]

Kurt Hugo Schneider I saw the same thing, but had to erase the filled in 5 after I noticed the mistake in this reasoning: this technique only works if the 4 pairs are present in only 2 boxes. Here each of the 4 pairs has it's own box, thus influencing the box house if either 3 or 5 is chosen. See Simons video on uniqueness for a more elaborate explanation!

[@JohnSmith-rf1tx]

No, having matching 3-5 doubles wouldn't be a uniqueness issue in this instance. Uniqueness is only able to be invoked if there is no way for other logic to disambiguate the pairs, i.e. when swapping the positions of the numbers in the pairs, it still leaves both numbers in the rows, columns, and boxes. But in this case, the pairs aren't in the same 3x3 boxes, so they are still able to be disambiguated. Sure, when you swap them you still have a 3 and 5 in the rows and the columns, but not in the boxes. Each of the 4 boxes ends up with a new number in it, which means that there is still outside logic that can tell you which way around it is actually meant to go. It was just a fluke that eliminating the "fake uniqueness" possibility didn't end up being an error.

[@smoemobile3]

I just wanted to say thank you for your channel. I very much enjoy watching the puzzles being solved. I especially love the enthusiasm , i.e. "watch, oh this is brilliant ", or "What an unbelievable puzzle", or even when the puzzle is described as beautiful. It's the highlight of the end of my day to see the amazing puzzles that are created and then solved. I am looking forward to watching this one now.

[@DJarr216]

It's gonna be hard to decide which is the best sudoku Simon has solved recently on this channel. "This is one of the best sudokus we've done on this channel". It's allmost becoming his catchphrase at this point.

[@wes_h1604]

Beautiful... absolutely stunning.. what a puzzle..

[@HeBro]

Oh yes, exactly!

[@blandingswest6560]

Simon's superlatives are warranted. His classic sudoku solves just get better and better. The quality of a sudoku is measured by the degree of satisfaction you get in cracking it, and the degree of elegance you can demonstrate in proving it. Both of which Simon achieves convincingly. Bravo!

[@Czeckie]

"[X] is a phenomenal puzzle-setter" I wish Simon would say, just once, "this is a great puzzle coming from an otherwise dogshit setter"

[@garanceadrosehn9691]

Beyond my abilities. I am getting good enough to notice one X-wing, but not two X-wings and a swordfish in the same puzzle, and then being able to keep all three of them straight in my mind. This is another puzzle where all I could do is watch you solve it!

[@marcmarshall2765]

I would like a mug that says either "What a puzzle" or "it's just stunning" :D

[@cha.felino]

“Holy moly” for me!

[@AnRuixuan]

sigh...I've resigned myself to the fact that I will never be able to solve a sudoku that relies on X-wings to make progress. I've been watching this channel for almost a year and they still trip me up every single time.

[@doctorwhouse3881]

I usually spot them, but I missed it this time... and proceeded to advance one number and then get stuck again.

[@ol1ver49]

Well I'm getting better at finding X-wings, and found these. But the swordfish defeated me - spread out over the whole grid. I don't think I'm ever going to figure those out.

[@sunriselg]

When I don't see anything, I go through the grid, colour every single place a 1 can (or cannot go) and see whether I can see singles, pointing pairs, x-wings or fishes. If I can't, I go on to 2, then 3... up to 9. Then I look in every single row, box or column for pairs, triples and quadruples. Then back to looking for fishy things on 1-9. Rinse and repeat. I also usually notate everything.

[@Intrebute]

Holy bonkers this one took me 45:15. It feels so nice to be able to crack one of these tough looking ones finally. I've learned so much from this channel, thank you guys a bunch :D

[@ShadowMark474]

34:27 what a fun puzzle, the x wings were easy enough to spot, but I didn't find the swordfish. That did force me to find more interesting logic regarding the other x-wings and triples and such, so I'm kind of glad I didn't find it. I also saw that there were opportunities to use uniqueness (for example the bottom row of the 3 x-wing couldn't be a 35 pair, so the 5 had to be in r7c6) but they weren't necessary. All in all one of the best classic sudokus I've seen from this channel, and it just goes to show how much better handcrafted puzzles can be than computer generated, shame that we don't know who set it.

[@ThatGuy-dj3qr]

You are right. There are almost always multiple paths to a solve.

[@Julesoby]

I saw the same thing, but had to erase the filled in 5 after I noticed the mistake in this reasoning: this technique only works if the 4 pairs are present in only 2 boxes. Here each of the 4 pairs has it's own box, thus influencing the box house if either 3 or 5 is chosen. See Simons video on uniqueness for a more elaborate explanation!

[@l3igl2eaper]

Coming back to these older videos and trying these puzzles is refreshing. The skills I've developed are paying dividends. Saw both X-Wings and the Swordfish almost instantly. Finished in around 27 minutes.

[@ariel_haymarket]

I'm seven minutes in and only filled 3. This is a good one.

[@erikivanenko1305]

It can also be done without the swordfish.

[@rogerhall4852]

This guy just flipps my bacon. He's SO polite..... the way he 'go-go's' over his puzzles. Love him....

[@Mithical9]

Just over 50 minutes for me - It took so long to spot the swordfish I had forgot about the x-wings, so it took a while to sort of overlay them on top of each other. Great puzzle.

[@user-cr4fc3nj3i]

1:33:39 for me. Spent more than 40 minutes to find out if C6R7 is a 5 or 6, because I didn't know the swordfish technique, but after that is just easy.

[@Psycho345]

I think there is a "bug" in the puzzle. If you assume r5c3-r5c7-r7c3-r7c7 is both 3 and 5 x-wing then the puzzle has 2 solutions. Therefore 5 must be in r7c6. It makes the puzzle very easy.

[@thatpuzzleguy]

I managed to solve this myself without guessing, albeit in forty-plus minutes. This channel has definitely made me better at spotting X-wings and their relatives. I did use a unique rectangle at one point to get a pair of 7s, but I don't think it really helped much.

[@Simoneadami]

New to the channel and almost new to sudoku. I tried it before watching the video. I stopped after a few digits. Then played the video e see the x wing. You explained perfectly. And then, alone, i spotted the second one! I feel so accomplished. I actually learning something. Thanks mate. PS Yeah, here in Italy we are blocked in house and o thought it was the perfect moment to try again with the sudoku!!

[@JuanMataCFC]

i thought i was decent at spotting X-wings & swordfishes, and then this puzzle comes along to stump me right in the face! :)

[@Raven-Creations]

I spotted the patterns, which I probably wouldn't have done were it not for all the other CtC videos I've been watching, but then I also used my earlier pencil marks, which meant that the puzzle fell apart in about a minute. I also made more complete use of the patterns to place useful pencil marks. This gave me a 58/68/56 triple in box 8, which came in very useful when mopping up. Simon, why do you spend so much time making pencil marks? You teach us how to place them, and how useful they are, but when you're solving yourself, you frequently place them where they are already resolved, and once you've placed useful marks you hardly ever use them! For instance, you had 18 marked in box 3, part of a 18/12/28 triple in row 3. You then placed an 8 in the box, but completely ignored the 18, despite hovering over it several times. Had you not ignored it, you could have completed the remainder of row 3 and cruised home. By the time you did eventually use it, you could have already finished.

[@BlueCyann]

This might be the first time I've ever found all of the logic in a Sudoku with this many fancy techniques. It took forever; I'm in awe of how quickly some people can spot these things. But I did it.

[@Qazqi]

15:37 and a very satisfying puzzle. I entered a few pencil marks before taking a second to look at the grid and realize there had to be a couple X-wings hiding in there. Ended up using four (actually three X-wings and the swordfish on 5s, but close enough) in total over the course of the puzzle.

[@harstar12345]

the first pattern with 3s I worked out another way, with the mirror of the bottom corner boxes. No matter which one of the 35 pair is a 3 it forces a 3 in the first row of them and ultimately forces a 3 in the highlighted square. Quite magical.

[@colleenscottcarmello5103]

OK sooo I found the 3-5 Xwing straight away.. and knew it was important, I just couldn't pull out the 3's .. ended up pausing the video and went about filling in some spaces to try to help.. Well this MUST be a (#) right here... and that makes this MUST be a (#) right here.. half way thru.. I knew I was in trouble.. back to the video to find Most of what I labeled as MUST BE, turned out to NOT BE.. Oh Lord.. lololololol.. Simon you are a pure delight to watch.. I have so much to learn.. :)) I must say that I hear your words in my head now, when I do the puzzles 'This MUST BE..." hahaha I enjoy these videos immensely. =D

[@sampathkumar-ej7xl]

I can only imagine the level of happiness experience when one solves this kind of sudoku on one's own. Brilliant effort. This has got to be the best sudoku I have seen with so many intertwined x-wings. There was a not very rewarding y-wing thrown in there plus the 3 column xwing (starfish?) that helped get the 58 pair in the first column. Just terriffic overall.

[@VictorCastillon1]

I found the X-wings but not the swordfish so I had to rely on some chains. I was able to solve it but in a less gracious way. It's always amazing to watch you find this patterns and solve the puzzles in an elegant way.

[@SvviftDeath]

57:13 This was a lot of fun to solve. Took me forever to match the 358 that finally solved the puzzle. Brilliant puzzle and one of the best I've seen from a classic sudoku.

[@khayman9574]

Man, that's been a tough one! 3 x-wings and 1 swordfish weren't enough for me; I needed a few triples as well but, eventually, I was able to crack it. I'm very satisfied with this puzzle and, admittedly, it's thanks to you guys that my solving technique has improved to where it is now. Thank you and keep 'em coming. PS. I've just watched the video and, obviously, you've solved it a lot more easily and rapidly than I have but I'm still happy that I eventually managed it without help. Thanks again.

[@glennmelven3414]

That was a fun puzzle. I get as much enjoyment out of the puzzle as I do watching Simon.

[@chrisb8698]

Ugh, nice solve, especially seeing the pair in C1. I keep underestimating the power of X wings.

[@cruisy82]

Wow! 1,5 hours, but I did it! Took me forever to spot the swordfish, but I'm proud that I did spot it eventually. I'm getting quite good with X-Wings thanks to your channel but I still have problems with Swordfish. I love your videos and your enthusiasm and the smile on your face when you hit the check butten at the end.

[@sakshamgarg8531]

33:07.really enjoyed it. A couple of naked singles that one has to notice which makes this puzzle a bit tricky. (lol,i didnt use any of the advanced techniques like swrodfish,x wing etc.)

[@LeCrenn]

That was fun! I solved it in 38 minutes, which is really good for me. I'm not a fast solver. I only was able to do that because I stumbled onto the trick with the swordfish.

[@MrSkopelos27]

Read some comments before starting and thought it's gonna be super hard but actually managed to get it in 15:58. Don't even think I found the swordfish, just worked with more basic logic. I hope that doesn't mean I used wrong logic and still got it right!

[@aaronfreeman3901]

48:18 X-Wings on top of X-Wings that require other X-Wings to figure out. X-Wings showing up triples that show up other triples that lead to pairs. Fun solve, what a rollercoaster. After watching the video I can safely say i definitely didn't notice the swordfish wow.

[@dragnl0rd]

47m47s without watching the video! I think even more noteworthy is that this is the very first time I've noticed a swordfish without being explicitly told about it.

[@GabeWeymouth]

Got it in 35:38. My solution method was pretty different though. I placed that 7 in r6 much earlier to avoid a nonunique solution in 3/5s.

[@Tempus0]

I got 3,5,8 locked in to rows 1,9 and columns 2,5,8 from the x-wings and swordfish combinations, and from there is was an easy finish filling in the rest.

[@MrSaydo17]

48:44 - so happy to find the swordfish

[@12tone]

This one was brutal! So many wings and triples.

[@megaminxpll]

Not that crazy as you might think, but a harder puzzle than usual. Used 2 Xwings, a tripple, a 2-stringed kite, plus normal stuff, 6:07.

[@ChooseABetterName]

Dang dude you're a beast keep it up.

[@brachypelmasmith]

surprisingly easy and straightforward (puzzle interface makes it easier to spot swordfish) - 25 minutes.

[@venureddy1092]

absolute gem....

[@hopehigh3224]

14:40 but used uniqueness many times. After watching video I solved it totally different without using any X wings or swordfishes.

[@liiiinder]

I just used uniqueness on the r7c6 5 but damn Simon really nailed it without!

[@Grimba86]

Such a brutal but quite a clever puzzle. Took me an hour to find the trick to make it collapse. Guess i need way more practice. Missed the damn x-wings again as well.

[@Leo-tc1vb]

17:51 i spotted the x-wing 3s and the uniqueness logic for the 35 pairs rather early. One of my fastest solve honestly. Usually takes over half an hour

[@Leo-tc1vb]

And im not proud of using the uniqueness logic as some people frowned upon the logic, but still solved the puzzle nevertheless

[@thedizzyexplorer]

Here's another method exploiting uniqueness: After identifying the X-wings with the 3s, ask where a 5 can go in row 7? It is either in the middle box or NOT in the middle box. If the 5 is NOT in the center box, the threes are forced into either R7C3 and R7C7. This presents a uniqueness problem, as you'd have four perfectly aligned 3/5 pairs. Therefore the 5 must be in the center box of that row. In which place? R7C6 is the only one left. This allowed me to resolve the 5/8 pair in C5 and place an 8 in C8 without more thought.

[@RandomBurfness]

Sorry to burst your bubble here, but that's not a proper application of the uniqueness principle. The reason this is not a proper application of the uniqueness principle is that the four cells are all in different 3x3-blocks, which could mean some digit you find in a 3x3-block could disambiguate the pairs.

[@thedizzyexplorer]

@@RandomBurfness Ah, good point. Thanks for pointing this out!

[@Blindpig14]

Simon, you make everything seem so “intuitively obvious”

[@linggao2602]

I required only the clue of x-wing in columns 3 and 7, then used uniqueness to fill the 5 in c6, then the puzzle unwound for me. Took me some 13 min. But I wouldn’t have spotted the x-wing on my own though.

[@Wouter10123]

38:39. I found loads of X-wings and swordfishes; a very satisfying solve.

[@johannespalmberg4062]

Love your enthusiasm!! brilliant solve

[@yiotatort]

This one was so odd, I've either watched you do a puzzle with a very similar design or done a puzzle myself very very similar to this one. It was very deja Vu. I even hunted back through the puzzles I've watched on this channel to see if I could find the puzzle I was thinking of.

[@sunriselg]

35:22 for me. Swordfishes and Triples seemed to be the theme of the day.

[@chrisdark999]

So I am OK at Sudoku's, however on this one I saw the super symmetrical pattern and immediately thought 'swordfish', and found THREE of them, for 3, 5, and 8 In effect this was similar to how Simon did it, however it was possible right off the bat, and then you eliminate tons of 3, 5, and 8 squares And then by marking up the numbers, the 'tricks' Simon found just fall out pretty neatly It took me 64 minutes still, but I did it!

[@DNXTMaster]

I somehow found the 5 swordfish, the 3 x-wing, and the 8 x-wing but could not finish the puzzle as elegantly. I ended up finding a skyscraper pattern that allowed me to eliminate an 8 candidate from the bottom left corner of the 3 x-wing, creating a 3-5 pair that broke the puzzle for me

[@dmdeemer]

54:26, but it was a good solve, found the X-wing and swordfish. I just got hung up on noticing pairs and triples after that.

[@richardfarrer5616]

Got the two X-wings, got the swordfish, got the 358 triple in the top row. All seemed quite easy. Spent over half an hour before I filled in most of the possibilities and spotted the 58 pair in the first column. Why did I miss the easiest combination in the puzzle? :-(

[@mariamoonbeam]

39 minutes. I wasn't sure if I would be able to solve this one since it looked like it would rely on swordfishes but since I knew that was the kind of thing I was looking for, I made it through.

[@ArunIyerS]

Spotted the 8 X-Wing, spotted the 5 swordfish and for a long time did not spot the 3 X-wing at all, I looked at the video, and Simon spots the 3 X-Wing first and I am facepalming hard :-D

[@korbinorion6263]

Any chance of adding a text box to the left side of the puzzle for taking notes? It would really help plebs like me who can't keep track of so much info in their head for harder puzzles and then this way I don't have to leave the web page to check said notes.

[@Socialdogma]

I spotted the first 2 x-wings and intuitively I knew there were other patterns in play but that’s as far as I got on my own.

[@ByronIgoe]

Just under an hour on mobile. I found a couple X-wings and a swordfish, and used uniqueness once.

[@abhaymenon1667]

took me 90 mins to solve it.. didn't know the swordfish technique. But I am so glad I solved it

[@TerryPullen]

Truly a beautiful thing. Wow!

[@StevenJacks]

I'm having an issue with the editor. It's when using the numbers across the top of the keyboard and then the numbers in the number pad. Ctrl-numbers work just fine to place a little number in the center. Shift-numbers only work if I use the numbers across the top of the keyboard, and places the little numbers in the corner. If I use the number pad while holding shift, the number still appears big (a normal filled in answer). Can you look into this please? I'm using Chrome on Windows. Thank you very much for your attention. :)

[@grenvillephillips6998]

Simon really does like his fish!

[@richardhenrysutterrosendo3439]

39:54 I'm very happy to have spotted and been able to use the x-wings

[@michaelb6349]

at 17:48 you missed the basic elimination causing an 8 at (2,4). I love how you skip straight to the advanced techniques!

[@michaelb6349]

Also love your enthusiasm!

[@tomasouzaheuert]

The absolute logic he built to find that eight in column two Holy cow

[@kurzackd]

12:22 - psycho evil laugh :O

[@rabidsamfan]

18:31 I surprised myself by actually spotting the swordfish and a naked single early on.

[@spelldaddy5386]

Holy shit that was a crazy puzzle. Thanks Simon

[@iliaschakour3171]

I didn't spot the swordfish but still managed to solve it without bifurcating , i loved this puzzle

[@StephanSpelde]

Missed the X-wing on the 3's, but spotted the X-wing on the 8's, the Jellyfish on the 5's and the triple in row 1 early on. (partly because of the "training" I've got from the Classic Sudoku app) Thought I solved the puzzle within 45 minutes, but turned out I made a sloppy mistake somewhere early on. :( Nevertheless one of my favorites Classic Sudoku so far!

[@chrisdwyer9570]

He says "That is one of the most beautiful things I will see this week. It is absolutely stunning!.........but does it help us"???

[@AngrySanta]

Tried this 7 different times using what I thought was solid logic. Failed each time. Ran into conflicts every time even with careful pencil notation

[@lebrigand4115]

I could have died of old age before figuring this one out.

[@STDimeanSTUD]

Brilliant!

[@valeckseimu3132]

Beautiful!

[@Samusin.]

… i am a bit confused, at about 16:45 you say the x-wing was affecting the columns, but the way that sounded (at least to me) like this isnt always the case, but i sort of always thought an xwing (or their expanded forms) always rule out the numbers from the rows aswell as the columns so now i am questioning if i tried to remember this wrongly or so... please one of you briliant minds help me lift my confusion

[@JakeDiToro]

From a technical perspective try do eliminate from both the rows and columns. From a practical perspective you already have to be in a position where you've eliminated the number from the rows to define the xwing which effects the columns, or vice versa.

[@JaggerG]

I didn’t spot all of those. I did find a rather odd pattern that’s probably a result of all of those, though. I got to some points that required me to realize that there had been some kind of 358 quasi triple in boxes 7, 4 and 1. I had 58 in c1r8, and 358 in c3r7, and 35 in c2r1, and 358 in c1r2. Another 3, 5, or 8 had to be some place in c3 in box 1, and either position it could have been in joined the 35 in c3r5 to eliminate 3, 5 and 8 in c3r8/9. There *then* had to be a 3 or 5 in r9 in box 7, joining the pairs in boxes 8 and 9 to form yet another 358 quasi triple, limiting box 9 r9 to only 246, joining c9r8 to form an actual 246 triple. That then forced c7r8 to be 358, joining other cells in c7 to form another triple that finally forced c7r3 to be a 1, and I think it crumbled from there. It felt pretty absurd. Not sure if I’m glad or disappointed there had been another solve path.

[@JaggerG]

Oh yeah prior to that, I had 3567 in box 4 lead to some strange X on 6’s and 7’s there and in box 7. There might be some logic principle to it, but it had been a little chainy.

[@TomCarberry413]

Very interesting but by focusing too much on the x-wing you missed the obvious 46 pair in the top right, which solved that entire square almost right away. Too clever. Enjoy your videos. Thanks.

[@praematura]

19:05, but I made an 'educated guess' at one point to help unstick myself. Still happy with the time, though!

[@selenasilverstep7981]

1:21:31 for me. This is X-wing hell. Imagine not being able to color your paper to solve this one.

[@thomaswilke6312]

Great lesson

[@valeckseimu3132]

My first number i put in was the 6 form naked single at 15:38 ! But looking at the simmetry and number postion so at 2:54 i realize dat something very wingfishy was going on here

[@davidh.4944]

41 minutes. I caught all the fish, but had a harder time hauling them in.

[@danielbreiner9830]

That was really hard :D Managed to get through it, but took me quite a bit longer than you :D

[@alastermyst]

34:35 but had to do the guess and check because I couldn't see a logical path forward after 25 minutes or so.

[@JayK-wb8fm]

6:07 can someone explain to me why the 3 he put in the second grid can't go in the spots above the ones he put the 3 in? The x-wing and the 3 in the central square dont exclude those spots

[@NA-cx5zm]

There could only be one position left for the three in the third row after eliminating 3 from 3rd and 7th columns with the x-wing.

[@DevilishlyDutch]

"Wasn't monstrous to spot" yeah so I did not spot that until you pointed it out, and even then I didn't spot it was an X-wing, I just kinda went 'what happens if I put a 3 in r3c3 or r3c7' and found it couldn't be there, but I still hadn't realized it was because of an X-wing T_T

[@draconicdusk5911]

This was so tough! even when spotting all the X-wings it took me 92 minutes!

[@raswartz]

34:17 - Getting the 5's and 8's was huge.

[@selueen3028]

Damn, I missed the second xwing (the one with the 8s) and got stuck. But to be fair I'm not familiar with swordfish pattern so I would get stuck anyways.

[@BLAG0PS]

In my world x-wing is used by the dark side of the force in sudoku

[@GordonHugenay]

Didn't spot the 3-X-Wing, but still somehow managed to finish it, I spotted a 3-swordfish somewhere instead.

[@iosifoulis]

22.01 ty for the puzzle

[@edensaquaponics1941]

I managed to get 3 digits and 9 cells containing matched pairs. Although I spotted the X-wing on the 3s, I failed to see the significance.

[@MTTR01]

I dont understand why the swordfish interacts with the 8’s?

[@tcarni21]

M01 draw the 8s x-wing. Now draw the swordfish. You will see that the “forbidden” cells match. The 8s and 5s have only 2the same 2 spots to go

[@KumaKaori]

13:55. WOW. that was a detour and a half, but /worth it/ (14:36, and is resolved due to a naked single over in r4c8. ;).)

[@masheroz]

I top out at using x wings, so I wouldn't make any progress on this. Also, I haven't seen you this animated for yonks.