[Extreme] A Sudoku With A Sting In The Start! 

dude talking about splendid patterns and amazing configurations while i sat there trying to understand a "swordfish"

This one is way beyond my pay grade.

You should look in to an eye tracker, would be fun to see.

You know what would be awesome? Videos showing examples on how to spot each pattern type (swordfish, skyscrapers, finned fishes, chains, loops, etc). There are pages out there describing each of them, but they're sometimes hard to grasp and I think they would be a lot easier to understand if we hear you explaining them!

This classic sudoku deserves more views. Lovely puzzle.

I'm surprised you got through it without ever noticing the 3 & 6 swordfish cause it had the same pattern as the 1 & 2.

Wow, this amazed me, you're a genius ! Well played !

I plugged through numbers and found oodles of swordfish. Manually colouring in all the one's possible, then each number in succession. Repeatedly! Then got stuck for quite awhile. I am really proud of myself for persevering and solving it. Can't wait to see how Simon solves it. I'm sure it will be above my paygrade.

This is a good warm-up puzzle for Tattooine Sunset, based on all the swordfishes in both puzzles.

Watching you solve it, as well as the computer's solution, this sudoku is incredible. There are 5 different swordfishes that could be spotted.

As we rounded the home stretch, I was terrified there'd be a contradiction - well done! I'd love to try another like this to see if it gets any easier. Thanks for a very enjoyable challenge.

I spotted like five swordfish but then spent ten minutes not noticing a hidden single.

Learn more from these very hard ones! Great job! Brilliant!

I was actually wondering while you solved it whether my assumption was true that there would be a similar sword fish for 3s and 6s as there was for 1s and 2s, since they shared a similar setup (being offset and both numbers sharing a row). Dismissed that thought, because you didn't pick up on it. So even while I could've never solved this one at my skill level, I'm a bit proud of myself for spotting that :D

Absolutely brilliant solve. Probably my favorite video so far

38:46 Honestly surprised i was able to solve this one, and in under an hour to boot. absolutely wild. starting off with *5* swordfish is unbelievable.

i dont even understand what a swordfish is, mich less how to spot it. and here you are, finding 3 and working through them. serious props to you, sir

36:13. And pleased with it! What a crunchy start! Now to see how you avoided either/or, which is all that saved my bacon.

For the first time in my life I solved a puzzle faster than Mark or Simon. Bifurcation for the win! 😇🏆

I did this one in a site that has automatic pencil marks. There are lots of fish in this one including finned and sashimi fish and several AICs. It took a while to get going but then it collapses pretty quickly after. Nice puzzle, thanks for posting it.

That was quite the puzzle! After using the video to get a hint about the swordfish on 7s, I found an additional x-wing on 7s allowing me to place the 7 in box 9, unwinding several pencil marks and cracking the rest open. Very enjoyable.

I am a great fan. I love that you show us how you solve a puzzle that you haven't seen before. So don't feel sorry that you take your time. It just shows us how you get the job done

After running through slot machines on 1s, 2s and 3s, this puzzle resolved for me in 24:00, no swordfish required.

The slot machine technique gave me a bunch of 36 pairs and 12 pairs. Beautiful puzzle!

This puzzle was waaay above my skill, but I love watching you explain the logic for these puzzles. One thing though I've got to ask: @10:00 you show the 1-2 pair for sub-grid 8. I immediately saw that you could do the same for sub-grid 3 and 4 where no 1s and 2s are present either - am I right? Wouldn't that have made things easier? Anyway keep up the good work with your puzzle-solving and your videos. They are always nice to watch! :)

Amazing solve of an amazingly difficult puzzle. I stood no chance of solving it myself, but it was a pleasure seeing it solved.

Wow, hats off for seeing this.

Congrats - a great solve under pressure!

I found a pretty easy tactic for this sudoku, no swordfishes required- just pinpoint the position of 1 in block 4- two chains will do it (pencil-mark, if you want), after that all 1s, 2s and 7s will fall. Now fill in a given 9 in the corner and all 3s and 6s (pairs mostly) and rest of the 9s will fall too. Now all there's left is to mop up 4s, 5s and 8s.

I saw the swordfish on 3s and 6s and used the swordfish to find more hidden pairs that you didn't get.

Wow! Will have to digest this slowly!

Another great lesson

The layout of this grid was just screaming swordfish to me, and I had identified 4 swordfishes in the first couple of minutes (on 1, 2, 3 and 6-es). But I still didn't know what to do after that - I didn't find any weak spots, even with the swordfishes. I think if I had found the swordfish on 7s, and its interaction with the one on 1s and 2s, I might have cracked it. Sublime puzzle. I definitely want to come back to this one in a year or so, when I've forgotten all about your solve.

It took me 7 minutes to spot it. After notating the three 1/2 pairs, I decided I was done with this puzzle.

I need a LOT more experience spotting sword fish... I found a whole bunch of 'hidden rectangle' type scenarios where I found pairs of numbers within squares... but then got completely stumped because swordfish are completely outside of my comfort zone. This was amazing to watch!

Amazing, not sure if I’m ever gonna be able to spot something like this!

I tried solving this with the slot machine technique you mentioned. Still not possible without noticing the swordfish (which I didn't), but it did get me a bunch of pairs which got solved after finding that initial 9 in the bottom left corner via the triples from the 127 triple from the swordfish.

Double Puzzle Day!! YAY!! And both of them were tough. Triple YAY!!! I did solve it after watching you get started. Found some numbers earlier than you, but that is because I pencil marked before watching you puzzle through the swordfishes. Seriously doubt I would have started (can not finish if you can not start) without watching you do the hard work. Thank You!

What a puzzle! Definitely the kind I'm the most interested in (super difficult classic sudokus with no chaining strategies).

Gave it a go, got a few minutes into it, found 3 pencil spots same as your start, went "yikes" then hoped you could show me how to solve it 😂

I gave up on this one. Life's just too short.

No idea why this was recommended but I figured hey why not... And all of like 6 minutes into the video, I feel like I'm trying to swim across the English Channel. Against the current. In the middle of a thunderstorm. I can't follow any of this at all. :B

After getting your help on the swordfish on 1 and 2 I did exactly like the solver. Took me just over an hour to solve, so I think you were quick about it

Wow. My mind is blown.

I found out a lot of 1-2 and 3-6 pairs using the slot machine methods you guys showed some time ago but then got stuck. This one is a real head scratcher!!

Wow, this was awesome to watch

Very fun puzzle! Solved it in just over an hour. I am proud that I found the all the swordfish on my own :)

Couldn't even start this sudoku. But after you showed the swordfish I went back and found another 3 overlapping swordfishes in the starting arrangement

I went with slot machines on 1,2,3&6 at the start, which was very productive, nets you a few 1,2 and 3,6 pairs, and more pencil marks than Snyder notation could get. Coupled with two swordfishes on the 7s it was enough to crack the puzzle, but it was hard labor right up until the final hidden triple. A little over 45 minutes.

Of course I didnt find a single digit, tho it was a really nice journey, following you along. I also started using colors after 20min of nothingness, I went and marked all spots where a 1 can never be, and afterwards all spots where a 2 can never be, I saw that these were kind of what I called them "racing tracks" and they had the exact same route so I tried to imagine if combining both routes would eventually break one position of a 1 or a 2 but my head just couldnt think that far ahead, so I went through all the other numbers and realized that there was nothing I could do to enter another digit. Its not the first time I saw a video thats about Swordfishes on this channel, but even if I understand them a tiny bit now, I can not imagine finding these on my own in a puzzle. But hey, at least that made it more exciting to watch how you try and solve it, and man was it exciting. Its weird for me especially because Im just a 21year old gamer who plays all kinds of games, lots of Indies with interesting new approaches, my favorite game being Ori and the Blind Forest, so I do know lots of exciting games, with action, with colors, with motion. I am not a fan of shooter games, dont worry. There has to be a story that I want to follow, that immerses me into the game, that can make me sad or happy. I hope Im not derailing here, because even tho I love using my brain to solve a puzzle, I didnt expect that I would subscribe to a channel like this one on youtube, that I would start doing Sudokus actively again, ... that I thought a Sudoku like this would be just as interesting as one of those games with action, colors and motion. This one here definitely had a Story and even if I couldnt experience it myself, you showed it to me, so that specific Sudoku kind of explained to me, why I seem to enjoy all of this. Super long comment of unuseful information. If someone cared to read this... uhh thanks, I guess? ^^

I chased down the slot machine for 1, 2, 3, and 6. I got a number of pairs and found swordfish which I pondered for a bit (30 minutes), then I finally broke a 1 and that got through all of them, then I got the 2's 3's and 6's. By the time I noticed the 7's that brought it all home. A stinger at the beginning?! How about a pike up the arse! Loved it. looking forward to the app on steam. Sandwich sudoku is brilliant!

I attempted this before watching without knowing most of these techniques being mentioned and did it in around 27 minutes using empty rectangle chains. I started with the 8th block and was able to relatively quickly find contradictions on the 1,2 pair which lead to unraveling most of the rest of the numbers. Even doing it "wrong" it was absolutely fascinating. Edit: And now that I'm watching your slot machine video, I just realized that was effectively what I did -_-.

35:51 for me. What an interesting puzzle. I used the slot machine technique in the beginning for 1s, 2s, 3s, and 6s, which led me to several pairs. The 127 triple in column 9 is what completely broke open the puzzle for me.

I managed 53:29 on this one. From what I can piece together (as a total novice at some of these techniques), I used the slot machine technique on 1's, 2's, 3's, and 6's to get snyder pairs in every relevant box, and then bifurcated from that 50-50 scenario to get the solution. Naturally, solving it through pure guesswork felt horrendous. I'm happy to see that there was indeed some gorgeous logic available to crack it open, albeit logic that is far behind my abilities.

01:18:31. Without help! I don't think I would've been able to solve this had I not stumbled upon your channel. I also now understand the feeling of finding a beautiful puzzle

It took me 1:13:53 to solve this one. Holy cow what a tough puzzle. I didn't find any swordfishes and instead had to get by with the slot machine.

I used the slot machine method you’ve shown before to solve the swordfish for 1,2,3, and 6. That got me down to Snyder notation in all 3x3 boxes for those numbers. Had to look at the video for the logic with the sevens, but after that it was so satisfying. Every new digit I imputed solved all cells of the same digit through x-cycles

1:49:16 and hell am I proud that I solved it at all :P. Wouldn't have gotten there without the "slot machine" technique that you explained in an earlier video (it allowed me to find a bunch of 12 and 36 pairs). I recommend that you try unwinding the slot machines, even if you already finished it otherwise, because it is quite fascinating to see how much it gives you here :).

Eventually got this with many many swordfishes. And an “undo until solvable” assist.

I did swordfishes on 1, 2, 3, 6, and later 7. Got all 3s and 6s figured out. Did a lot of triples and then I got stuck. Found something, but turned out I made a mistake and ran into something impossible. Damn. Edit: Turns out I had marked a square as "not an 8", when it was an 8. Had to peek to the end of the video and compare notes. Congrats! This is the first time someone got me to spend 3 hours on a sudoku!

fascinating! 😵

Thanks to Derek Neal and his Slot Machine logic, I actually was able to complete this one (after a bloody hour of staring at the grid). This was brutal. Going to watch the solve to see what I missed, but I expect it to be a combination of about 8 swordfishes and 5 Y-Wings or some ridiculous amount of difficult logic. Yeesh!

18:02 HE SPOT THE FIRST NUMBER !

So this is "pick your swordfish"... It's oddly approppriate, because a swordfish does have a sting at the start. ;)

Slot machined right away and got lots of 1-2 and 3-6 and a 3-4 pair that made the puzzle solvable. Now time to watch how Simon solved it.

Tricky puzzle. Solved it without seeing you work, but took me a while to spot the 7s that allowed me to get the things going after spotting the series of 1s, 2s, 3s, and 6s. And then took me a bit to recognize the links those 7s had with the 1s and 2s, where I had to recognize there were spots that had no choice but to be 2s or 7s. The 3 and 6 swordfish overlap as well, but not as well with the 7s, which really were the key to this puzzle as soon as you figure out how to use them in coordination with the 1s and 2s.

This was really something to watch you solve. I was able to solve it but it took me a couple of hours and Ive never heard of swordfish or any of the names you had for the strategies. Really interesting to see you categorize those types of patterns. Seems like everything is some angle of the pigeonhole principle. Without notes or colors this would've destroyed me...

If I hadn't seen the Jellyfish sudoku solved two weeks ago I never would have solved this. The grid pattern reminded me of that puzzle, and it led to swordfishes for 1,2,3,6,7. Took a while to double check all the logic, but then the rest of the puzzle was basically unwinding pencilmarks. Very cool puzzle.

I am subscribed and I have asked this before. What program are you using to insert the numbers ( corner, center and normal, etc)? I would like to be able to insert my own puzzles (from monthly magazines) on your program used on your tutorials instead of pencilling on paper. I really like your set up of giving us a chance to solve the puzzle you are working on before we follow your process of solving.

a very interesting observation, the hints allows for 4 Slot Machines right away, 1,2,3,6. Each one allows you to get a pair in every cage. Furthermore, the slot machines forms two links. 1 & 2 becomes a link, along with 3 & 6. Slot Machine 3 is also Linked to a 4-pair. They also "complete" a cage by allowing to place a 589-Triple. But after that I got stuck

That has to be one of the hardest Sudoku I've ever solved. Wow. Lots of swordfish, a handful of quads - neither of which I see all that often. I didn't place a single digit until I reduced it to a swordfish on the 5s (considering there are no 5s given, this took a while), then the puzzle collapsed completely. Great puzzle!! 24 minutes of fun.

yeah no i absolutely needed the clues you gave to solve this, i solved along and paused to see how far i'd get, and i did spot those 1/2 pairs! but... that's it lol

Wow. It took me an whole hour to solve this ... but I got there :-)

Didn't manage the solve myself, but there's 4 slot machines (1,2,3,6) which lead to 6 sets of pairs in boxes and not much beyond that.

Holy crap, what a nice puzzle. I did totally miss the swordfish on 7s and the 127 tripple… Once you pointed that out the rest fell into place quickly... Nice one.

What was called extreme on this channel a year ago might be classified as approachable now! It took me a long time to get any digits even after spotting many swordfishes, but Goodliffing and scanning got me chipping away and then it flowed from there. 46 minutes.

thrilling!

Nice one, got nowhere in the beginning but after you pointed out the first swordfish I could find the other one and solve it. A humble request: fix so that the mac command key also works for multi-selecting tiles in the solver app. CTRL on mac unfortunately opens the context menu.

If this was what all sudoku's were like, I'd never do another. I got a headache watching it and quit after about 15 minutes in, realizing I hadn't a clue what he was doing.

Three swordfish ate my brain - it wasn't pleasant!

Stared at this for so long until I broke down and watched the video and with Simon's help with the triple swordfish I could get the rest myself. I'm still proud of that much even though I know it isn't impressive in the slightest. 23:52 after starting over knowing about the swordfishes.

38minutes, that was a pickle. I wasn't sure how to resolve last bit but it seemed to work only one way. Watching video now :)

When you got the 1 2 pair in bottom center box, I saw a similar condition in boxes top right, and left center. I don't know if it matters. **should have waited to post... The solver saw it too

there are actually also swordfish for 3 and 6 all one column right from the 1,2 sword fish for a total of 5 swordfishs

I was very glad to have done the puzzle correctly... until I watched Simon's solution and realized I had no fewer than 17 numbers wrong...

I was a bit surprised he didn't notice there were lots of restricted cells because of columns/rows with different numbers crossing (for instance column 3 (172) and row 7 (346), which gives lots and lots of triples to be pencilled in.

Also the 3/6 swordfishes...I found them all, but did not have the skill to unwind them all...Stunning was an understatement

Sending you a dud puzzle is hilarious 😂

Solved it with 5 horizontal swordfishes (eliminating vertically) on 1, 2, 3, 6 and 7.

Just looking at the layout if the filled numbers, I'll bet there's like 10 swordfish-like setups. Edit: Looks like there can be a vertical and horizontal swordfish for each of 1,2,3,6, and maybe something for 7s

I will now look for swordfish, thank you.

Huh. Actually one of my faster clears! 14:15. Kinda proud of it though. Solved it with basic sudoku techniques though. The 2s in row 2 and column 8 bith lock a 2 in column 9 of the northeastern box. Tracing both column 8 and 9 down reveal that there's only one box in the southeastern box where a 2 can go, which locks the location of the 2 in the south center box. and it just chain reacts from there and you can solve for all 1 and 2s. From there, the 7s follow this same logic an the puzzle takes off... Main thing that got me though was the 34 pair in the southwest box

Once the 127 swordfish is established, normal sudoku rules place the 12 in one of the three corners of the top-right box, and the swordfish eliminated bottom-right corner leaving a naked 12 pair on the bottom-left and top right. That fixes the 7 in the 7th column resolving the 127 swordfish.

I have no clue what just happened but good job

So a swordfish is an X-Wing with 3 rows/columns? Cool!

I knew I couldn't solve it so I bifurcated in favor of the number that did the most damage, and it worked. Still needed a swordfish later on. That was fun.

You missed the inverted Chinese triangle guillotine on 1s 2s 3s 8s and 9s at 13:56. Which then allows a bent triple slammer on 7s and 8s.

Now, I don't know if I made a happy mistake in logic early on but I found this easy. There were a lot of 589 triples which helped to unwind the whole thing from early on.

It took me an hour to get one digit after finding a billion swordfishes, which I'm normally not great at finding. Then it put up another wall that I used a swordfish to get past. 10/10 would break my brain again.

Can't believe I solved this in 16.01 without watching the video through. Then noticed I missed something on my first number and totally fluked it.