The Worst Puzzle I've Ever Been Sent

** TODAY'S PUZZLE **
According to its rating on Logic Masters, today's sudoku (Foggy Knight by Die Hard) is an average puzzle with few exceptional features. The truth could not be more different: in our opinion this is one of the most incredible sudoku discoveries ever. The ruleset is incredible and it's a fog of war puzzle with nothing showing. Prepare to have your mind blown!
Play the puzzle at the link below:
app.crackingthecryptic.com/su...
Rules:
Normal sudoku rules apply. The grid is covered by fog and correctly placing digits may reveal additional digits. Each digit satisfies only one of the following conditions: a) It is exactly one chess knight's move away from at least one cell containing the same digit; b) It is in its own 3x3 box (3x3 boxes are arranged in normal reading order. So eg 9 in box 9 meets this condition). c) It is the digit 5. There is one exception: the digit in the very centre of the grid satisfies exactly two conditions. No guessing is required or allowed.
** NEW SUDOKU HUNT JUST OUT **
Join us on Patreon (for as little as $2) for a brand new sudoku hunt (called Lines & Shapes) - it was released on 1 Septmber. Closing date 20th September :)
/ crackingthecryptic
** NEW GAS PACK: VOLUME 2 IS OUT **
The new GAS (Genuinely Approachable Sudoku) pack is out on all platforms here:
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60 original puzzles by Clover, Bill Murphy and Philip Newman!! Earn party hats and dinosaurs with these brand new puzzles!
▶ SUDOKU PAD - Use Our Software For Your Puzzles ◀
You can input classic sudoku puzzles into our software and help support Sven, the programmer responsible for the wonderful user interface we all use to play these puzzles everyday. The app also comes with 12 handmade puzzles from us:
iOS:
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Android:
play.google.com/store/apps/de...
ALSO on Amazon: Search for “SudokuPad”
▶ Contents Of This Video ◀
0:00 Theme music & introduction
1:13 Puzzle reveal & Rules
5:34 Join Us On Patreon
6:13 Happy Birthdays
7:56 Start Of Solve - Let's Get Cracking!
▶ Contact Us ◀
Twitter: @Cracking The Cryptic
email: [e-mail]
Our PO Box address:
Simon Anthony & Mark Goodliffe
Box 102
56 Gloucester Road
London
SW7 4UB
(Please note to use our real names rather than 'Cracking The Cryptic'.)
▶ SUDOKU PAD - Use Our Software For Your Puzzles ◀
You can input classic sudoku puzzles into our software and help support Sven, the programmer responsible for the wonderful user interface we all use to play these puzzles everyday. The app also comes with 12 handmade puzzles from us:
iOS:
apps.apple.com/us/app/svens-s...
Steam: store.steampowered.com/app/17...
Android:
play.google.com/store/apps/de...
ALSO on Amazon: Search for “SudokuPad”
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[@DieHard111]

Die Hard Here. Thank you for the feature and the praise! I am so glad you solved this puzzle - I got as much enjoyment from your solve as I did from setting it. This puzzle was derived from another puzzle (Knight Shift), which you can find on LMD (a warning: this one is even more difficult) - but I had the idea that the concept would work even better as a fog-of-war puzzle. When I set the naked single 9, I knew I had to complete it!

[@longwaytotipperary]

What a fantastic rule set!!!

[@Paolo_De_Leva]

I can't imagine a more impressive and peculiar combination of such an original and masterfully described ruleset with such a cool, smart and magnificent construction. 👏👏👏👏👏👏👏👏

[@JaymanOttawa]

That was one of the coolest puzzles of all time! Bravo sir! :)

[@David_K_Booth]

I like the humour. You casually threw us the first digit like a dog biscuit, and we happily caught it, but then we found out we had to earn our supper. Lovely work.

[@kindlin]

@@David_K_Booth It was like an intro to the otherwise new and complex ruleset. By understanding the middle cell and the 2 rules, you get a small intuition for how the other rules interact on all the other cells.

[@charliec.6285]

My theory on poor ratings on Logic Masters Germany vis-a-vis Fog of War puzzles: Unlike other types, FOW puzzles can be brute-forced by trying digits until you see fog revealed. I've noticed that difficult fog puzzles on LMD are often "solved" by people who don't usually complete non-fog puzzles of comparable difficulty. If there are people who only complete a puzzle because of trial and error, I imagine they might be more inclined to give it a lower rating.

[@Robert_H.]

Sounds like they need an error score that shows how many wrong numbers a person typed in. I can't imagine who would end up going to the trouble of retyping the solution of the soduko with another account just to make a bad rating displayable.

[@Tahgtahv]

@@Robert_H.The problem is LMD doesn't have a Player, all you do is type in whatever digits are requested. For FOW puzzles, by the time you go to entering something on LMD you don't need to guess at the answer.

[@SilvrSavior]

Maybe a counter that is added to every time an incorrect digit is entered that can clear fog. The software is smart enough to check if fog is present then it clears it with a correct entry, then it should be capable of checking & tallying up all the incorrect entries.

[@charliec.6285]

The website doesn’t interact with any software. To mark a puzzle as complete you must enter a code chosen by the setter (usually the digits in a row and column that aren’t filled until the end of the solve).

[@_aullik]

The start of the puzzle is super easy and fog puzzles usually lead you on an understandable solve path. I got the 5 in the middle easily, then i made a mistake ruling out the 5s in the corner and placed the 1379 and about half a minute later i noticed my mistake but by then it was too late. I had a lot of fun watching Simon solve the puzzle, but it was definitely to hard for me and i should not have tried it.

[@bobstreet2491]

I was surprised at how long you made us wait before mentioning digits "mutually satisfying each other".

[@TiagoMorbusSa]

That was pleasing.

[@Umbra451]

This is the orthogonal snake touching all over again

[@bbgun061]

Those digits are VERY good friends!

[@sirgeremiah]

@@Umbra451 Absolutely. Simon seems so tame, then does this so blatantly.

[@brookepearson]

@@bbgun061 all I can think of is "and they were roommates" lmao

[@DieHard111]

Die Hard Again. Thank you everyone for your all comments. And a special thanks to Simon for his incredible enthusiasm which is highly infectious. A few points of note: 1) Yes, it is possible to deduce that the corners are not 5s as a first step (this leads to a contradiction). But this does not take you very far, and I'm glad Simon found the naked single 9 first - which is exactly as intended. 2) Yes, it is also possible to deduce that R3C7 is a given 7. This takes a bit of look ahead (bordering on bifurcation), but it is a valid (if unintended) opening. Again, I don't think this takes you too far. A number of people have noted this won't clear the fog around the given digit - that is a feature of SudokuPad to signal its valid, but not the intended step. 3) I recognise not everyone loves this puzzle. That's OK. Simon's reaction made my year!

[@michaelawilliams]

I love it!

[@grithog5399]

I really wish the rules had indicated that the fog won't clear if the digit is a hidden given. It really set me back a bit since I assumed I must have made an error. Right, the 7 doesn't take you too far, but it can set you back quite a bit if you assume you made an error. Having the fog not clear seems more like unfair than it does "feature," especially since there is no indication that the "feature" has meaning. A great puzzle otherwise. A rules clarification would have tidied it right up.

[@Freeeez3]

@@grithog5399 very likely that die hard didn't know either, since this is technically a bug in the software.

[@v0id_d3m0n]

​​@@grithog5399 it does say "*may* clear the fog" rather than "*will* clear the fog" which could be an obscure indication of this

[@grithog5399]

@@Freeeez3 But he’s saying it’s a feature, right?

[@PauxloE]

This was the fastest first digit I ever found, but then I got stuck.

[@lunaverse4977]

I've been watching this channel for a few weeks, despite not having played sudoku myself since I was about 12, and for some reason i decided that THIS was gonna be the puzzle i tried for myself instead of just watching you do it. I must reiterate: have not done this since i was 12, and am now an adult. It's definitely NOT a beginner friendly puzzle, and i don't know what posessed me to choose it, but i did it. Took me 4 hours, but i did it.

[@tessabrisac7423]

Wow, congrats!

[@lunaverse4977]

@@tessabrisac7423 the satisfaction was definitely worth delaying my dinner until 10 pm, although i don't think i should make a habit of trying to solve puzzles right before cooking.

[@mostman]

Nice!

[@sirgeremiah]

I've been a regular sudokuist off and on for years, but never anything other than standard sudoku, and never the really hard ones. I watched two of Simon's videos and lept head-first into these bizarre variant rulesets. I'm still not very good at them (especially when they are used backwards, as with the knight's move here), but I love it, anyway.

[@OsnofAhcor]

that was brave

[@pelahnar4]

Myvdad was reading a book about logic puzzles yesterday and asked if I'd heard of "Simon Anthony" who was quoted in the book and described as "making some youtube videos on sudoku" I completely blanked without reference to Cracking the Cryptic and said no, until it slowly dawned on me, the yes, I _do_ watch someone named Simon and...wait, yes his last name _is_ Anthony...

[@Schmogel92]

Interesting. If you copy the grid, rotate it around the center 180 degrees and add up overlapping cells you get 10 everywhere.

[@LithmusEarth]

Bro. That's so Wild.

[@athomasone]

Is there some kinda phistomafelesque thing that caused this? Or just some byproduct of the knights move constraint? Or Die Hard just made it that way?

[@melaniehall5885]

​@@athomasone I don't have the answer, but I'd guess it either has to do with some knights move black magic, OR the puzzle constructor figured out that it easily works that way, and did it because it was easiest to set. I'm leaning more towards the first one. Knights move can lead to weird logic shenanigans

[@simsplayer9952]

One other thing I saw is every # including the 5 has 2 boxes with the # in same postions.

[@jonotick]

Part of it is definitely a flow on from the fact the numbers obeying the box rule would add to 10 with their rotated pair

[@tarquinioprisco8459]

39:54 "2 is not 5, unless you turn it upside down" 😂

[@cerebralcomics]

Pretty cool how each individual digit is not only in its 3x3 box, but also in its cell. Amazing setting.

[@cryptikkcries]

OH YOU'RE RIGHT!!!!

[@mranderson978]

Actually the rules of the puzzle make this the only possibility, so Simon could have filled in those digits from the very outset. The knights move rule excludes them from being in any other spot.

[@challicerobinson6273]

@@mranderson978 That is what I thought too but was starting to wonder when Simon didn't get it. Only started to solve it myself when yelling at six months ago Simon through the screen didn't give him a hint...

[@S_Black]

The break-in can also be argued by the 5 alone (and not some other digit). 5 automatically obeys rule C, but normally each digit can only obey one rule. Not two. So 5 in box 5 breaks that. The only way around is that is using the exception for the center digit.

[@thezanycat]

I’d argue the 5 isn’t the break in at all, rather Simon’s second placed digit is the true break in

[@0LoneTech]

​@@thezanycatBeing a bit stuck right there, I agree.

[@bananaman2]

I loved the symmetry of this puzzle and noticed early on how the positions of paired digits (1+9, 2+8, 3+7, and 4+6) swap places when rotated around the grid. I imagine that must be a consequence somehow of the knight's position requirements but I can't begin to plumb the depths of that logic.

[@deadeaded]

Reading the comments on LMD, it seems like the low score was because there was a technical issue with the software, which our lord and saviour Sven promptly fixed, as usual. Thanks, Sven!

[@RichSmith77]

Isn't there still an issue? I managed to deduce r3c7 was a 7 early on, by basically testing all permutations for placing 7s in the grid (after the initial 5 on the centre). I couldn't understand why it wasn't clearing the fog. I assumed my deduction was wrong, so I spent half an hour going over the same logic again and again, getting the same result. I eventually discovered it *was* a 7, my deduction was correct all along, it just didn't clear the fog as I expected because there was also a hidden given digit in that cell! (I'd coloured the cell, so it wasn't noticeable to me that the fog was cleared in the one cell. I just saw it wasn't cleared from the surrounding 8 cells.) I can well understand the low rating, even though it's more a software issue than a puzzle issue.

[@JK7H]

​@@RichSmith77 the cells with given digits are not meant to be brute forced, therefore the fog doesn't behave the same way.

[@RichSmith77]

@@JK7H You think it's a deliberate decision that the fog behaves this way, to punish me for not being smart enough to work out the logical path that Simon and others smarter than me could? I could forgive a simple software bug, but if I thought this was a deliberate intention, to make me waste half an hour looking for an error that wasn't an error, I'd downvote the puzzle no end. My way was "logical". It just involved a lot of case checking, very methodically. r3c7 had to be the 7 in box 3.

[@thesecondderivative8967]

​​​@@RichSmith77 To be fair, the instructions said that a correct digit *may* reveal the fog. Not will reveal the fog. It isn't the creator as much as it is you that put yourself in that situation. When the cell cleared but not the fog around the cell, it's pretty logical to assume that that digit is not going to clear the fog so long as you know your logic is correct. You didn't read the instructions properly.

[@RichSmith77]

@@thesecondderivative8967 Sorry, but I think it's you that didn't read the instructions correctly. It doesn't say it may reveal the *fog*. It says it may reveal *additional digits*. If you have done fog of war puzzles previously, the expectation is that a correctly placed digit will remove the fog in the surrounding cells. The "may reveal" comes about because those revealed cells may contain further given digits, or they may be empty. To be clear, I'm not blaming the puzzle constructor. I'm pointing out a software bug.

[@pedrosaraiva1411]

Normally fog puzzles are easier for me than any other variants, because normally you have always some numbers or lines already revealed ,so its easy to understand were to start. But this one was absolutely brutal, because you even after put the 5 in the middle square , you really have to work hard to know where to look net.

[@Valkhiya]

So this is really funny, I actually found a bug (?) in the fog logic. In a board position very similar to 34:16 in the video, I deduced that r3c7 had to be a 7 (the 7 in box 4 helped me reach that conclusion), so I wrote down the digit, but because it's a given digit it actually just revealed that single cell and not lifted the fog around it.

[@dannyzwolf4546]

I think that works as intended, but you did stumble on an unintended solve path.

[@tenientebustillos4019]

This happened to me as well. It was not an actual guess but a deduction. Had to check the video to verify my input was correct.

[@AnaFromTheShire]

Ahhhhh my happy place, just as I've gotten home from a super hectic day... As someone with high anxiety levels which affect my life in multiple ways, Cracking the Cryptic, Simon in particular, has been an absolute godsend. I can feel the tension leave my body as I watch him go into battle with each puzzle. And on a personal level, his gentle and gentlemanly manner, compassion and wholesomeness are like a hug for my mind after dealing with a wild and sometimes terrifying world. I'm wrapped in warm blankies, got the cats lined up along me, hot choccy in one hand, and a big smile on my face! Thank you so much Simon and CTC, arohanui from New Zealand

[@RenameJames]

I love watching how excited Simon gets solving these puzzles. I can't help but get excited right along with him. This was a beautiful solve to watch. Simon was very Simon in this video.

[@brianarsuaga5008]

This was too hard for me to do fully alone, but I'm pretty sure this is my favorite puzzle on the channel yet. It's just so elegant, and it really felt like I was.. not so much teasing apart a beautiful knot, but being given a tour of this beautiful knot that someone discovered exists in nature. It was also amazing how many different ways you could apply the mutually-exclusive conditions, when at the start of the puzzle they seem to be saying nothing at all. Truly an achievement, thanks for bringing this to us all

[@bobblebardsley]

29:26 "And this is going to be lovely, because it's going to allow us to sing 'Ah, You Rotten Thing'." All together now...! Ah, you rotten thing! How dare you give me naught? How dare a digit bring less logic than it ought? I went the long way round to prove what you must be, and yet you, rotten thing, gave nothing back to me. Bobbins, bother, blast! I loudly vent my wrath while moving not-so-fast along my logic path. Now digit, can you tell how grumpily I sing? You scoundrel of a cell; You rotten, rotten thing.

[@ChasePhillips7]

Simon, you are a treasure in ways i can't possibly describe. You and Mark and your partners absolutely have an invite, thank you so so much for saying that about me and Cheryl and Vegas! If you need a physical invite, send me your mailing address and I'll prove it!

[@emilywilliams3237]

I am so glad that this channel solves these very hard puzzles on a regular basis. I always learn something about how to think logically, and, when I think about it, I realize that it was not all that long ago that a thermo sudoku would have seemed hard to me. So maybe these more complicated puzzles are aspirational for me in the same way that the types I once found difficult are now not all that difficult. Simon, the grid coloring, your reasoning and explanations, and all of your pencil marking all served to make this puzzle make total sense. Am I going to turn around and solve it? Not today. But sometime, maybe ... Oh yes, one more thing that was impressive was that the fog was meaningful in this puzzle, and because it was completely fogged over it did not lead the witness, so to speak, as much as other fog puzzles often do. Thanks so much, Simon. I loved it.

[@bobblebardsley]

Agreed, and why I don't complain about hour-long videos even on days when I don't have time to watch them in full, I'll always try to watch the break-in and learn from that. I'll usually only attempt the puzzle if the video duration is less than 30 minutes AND I understand the rules, otherwise I'd still be solving it by the time tomorrow's video pops up!

[@davidmiller9485]

@@bobblebardsley Which is cool and all but I like the longer videos because I get to see Simon solve using various form of logic (form being used sorta loosely here). That's the great thing about recorded video. You get an opportunity to watch the video based on the time constraints that each person may be dealing with.

[@Sidnv]

"Deadly pattern somehow resolving itself": Simon, Die Hard gave you the digit that resolved it :)

[@altaybatuhan4560]

26 minutes in MY MIND IS BLOWN WHAT IS THIS PUZZLE

[@thecalculusofexplanations]

I would love them to use some sort of eye tracking software for a solve, I think that would be fascinating.

[@awilliams1701]

I noticed that each digit had to appear in it's own cell in its own box. when the box positions are numbered the same way.

[@radvermin1541]

Was getting frustrated with the extra hard sudokus I was attempting. Found your channel and saw how to think through the harder ones. I can solve them through simple deductive logic rather than guessing. Thank you for your channel. I'm enjoying them again.

[@TheDecagn]

I came to get a hint on this puzzle as I got stuck when the number 7 in box 3 (bottom left of box 3) did not reveal fog. After looking at the correct digit that simon put in, i saw that it is the same as I put in, so I’m annoyed that i spent so long trying to decipher why I was wrong when in reality I wasn’t, but the fog just decided to not reveal the surrounding area for some reason EDIT: after following through, I recognise that i managed to decipher that a 7 was there even though it was already given (after you clear fog), which is funny as from what I can tell, that 7 did not need to be a given!

[@JasperJanssen]

Maybe it was given precisely to avoid fog lifting?

[@guyb7005]

49:18 I'm shouting at my screen "7 in box 8!!!" but alas, I am too entertained by your articulate wit and eventual mastery

[@Rob-oj9bj]

One issue I came across while solving: If you put a correct digit in the puzzle which is also a "given" under the fog, it no longer clears fog AROUND the filled in cell. Not sure if this is intentional, but the first time it happened I thought I had made a mistake (filled in r7c4, nothing around it was cleared. Only indication that I had a correct digit, I realized after a moment, was the digit was black and not blue.)

[@RichSmith77]

This issue caused me to waste half an hour rechecking logic that was correct all along. (Wasn't helped by having pre-coloured the cell, so the fog lifting just in the cell wasn't noticeable.)

[@rokualvin6428]

You have multiple nearly superhuman skills. It is a given that you have a brilliant mind for solving Sudoku puzzle. But you also have an incredible gift of sharing your thought processes on the fly. You bring the viewer along with you as you work. This combination is fantastic for a KZbin Channel. And finally you have an enthusiasm for what you are doing, that is infectious. It is like a treasure hunter following a map, and feeling joy at each intellectual discovery, and not only feeling the glee of discovery, but sharing it with the viewer. I truly enjoy watching your videos!

[@steves1371]

I did it in 82:25, my first solve of a puzzle from this channel!

[@Bonehead777]

Someof the ratings on logic masters are just wrong because it depends who has solved them. There are definitely some folk who solve puzzles and just give them terrible ratings. No idea why it means that much to them. I have literally watched updates on a few of my puzzles and noticed big drops in ratings with certain solvers. And I know when I have created something that in no way deserves the lowest marks. I will bet that I am not the only one who has spotted this. Of course, the vast majority of solvers are completely fair so if a puzzle has a lot of solves, it is much more likely to get a fair rating for its’ quality.

[@deadeaded]

One of my favourite puzzles I've ever set was getting a lot of early solves (which is unusual for me, so I was watching excitedly), but then one solver gave it a zero, dropping it down to an 80-something, and suddenly all the action stopped, presumably because they saw the score and were scared off.

[@charliec.6285]

I think that's just the riSK OR Peril setters have to be comfortable with when posting their puzzles there.

[@Bonehead777]

@@deadeaded yeah,it is a real shame. Won’t stop me posting though. 🙂

[@Bonehead777]

@@charliec.6285 It is. Hopefully, eventually I can get enough of a name for good folk to always have a try. 🙂

[@BigAsciiHappyStar]

Ouch!

[@davidhughes7174]

A fog of war puzzle that turned into an amazing sudoku puzzle that ended up being re fogged in blue. Astonishing, again. Thank you Die Hard and Simon.

[@hewholimpsmartin]

That is terrifyingly amazing Excellent solve

[@iancastro2414]

Fun fact, it's possible to prove that the corner digits are 1, 3, 7, and 9 without using the numbers "given" in box 5. You can only put 1 in row 1 in the cells R1C1 or R1C2, if you try to put in any other cell, you will get the following: * R1C1 will be 5. * R1C9 will be 3. * R1C2 will be equal to R2C4. * R1C8 will be equal to R2C6. And there is no place to put 5 in box 2. If you apply this to column 1, you will have that in column 1 the 1 can only be in R1C1 or R2C1, so to satisfy both conditions the 1 must be in R1C1. The same applies to 3, 7 and 9 for cells R1C9, R9C1, and R9C9, respectively.

[@NeilCrabbe]

I haven't got to let's get cracking yet, but my first thought when I saw a completely blank grid is there's a 5 in the middle. Then I read the rules and I still think there's a 5 in the middle. Is this the Dunning Kruger effect? Have I been watching CtC long enough to think I know what I'm doing?

[@titusadduxas]

I assumed 5s couldn’t be in the corner because I thought that with knights move puzzles Phistomofels theorem stopped the centre digit being in any of the 4square corners.

[@RichSmith77]

Sorry , but that's not the rule. If a digit is missing from the Phistomefel ring, then it has to go in the centre. But this only applies that way round. It does not mean the reverse, that a digit in the centre cannot appear on the Phistomefel ring.

[@SuperPlienie]

I like all the puzzles but the fog ones always make me very happy!

[@eddieharwood7788]

That was a really hard break in, but the thing that really held me up was nearing the end when a 9 failed to clear fog. I deleted a long way and got to the same point, so I went back almost to the beginning and still had the same problem. Then I though that perhaps I had accidentally coloured the cell with dark grey and lo and behold the gog disappeared. What a numpty!!!

[@dannystirling5458]

This puzzle was an amazing watch! My favorite moment was my realization that, with only 1 one on the board, the pink squares at 51:11 had to be a 1, since every other digit breaks a rule.

[@leeway3739]

During my solve I think I found a glitch in the programing. I was able to place the 7 in box three via sudoku, but because there was a "given" 7 in that spot, it didn't clear the fog from the surrounding cells. Something maybe to look into?

[@ianward71]

Wow.. what a beautiful puzzle and a great solve by the maestro. Kudos to Simon and Die Hard

[@VeritasUnae]

Such a sublime rule set. Very cool to see this solve, even if I didn't have the time to spend giving it a go myself tonight.

[@altreusplays]

This rule set is tremendous! I love the device of requiring each cell to meet one rule but not more than one.

[@pianissimo7121]

the box number digit always has to go in its own cell, ie, 1 in box 1 goes in cell 1 and 2 in box 2 goes in cell 2 etc. This can be done at the very start itself without needing any other clues simply because of the ruleset. That is amazing. Edit: I might be completely wrong. Need to check my logic. If someone else can prove/disprove me please feel free to do so.

[@adrianhead6272]

I thought that too. It just seemed so obvious and yet no one (Simon included) mentioned it. It's probably why it got the average rating.

[@pianissimo7121]

@@adrianhead6272 i didn't find that logic myself. I only got it after Simon pointed out how row 1 and column 1 works with the rules. What's funny is i thought Simon would find this when he mentioned about the 1,2,3 and 5 being in their own cells and then he forgot about it.

[@RichSmith77]

Why does 1 have to go in position 1 in box 1, etc? That doesn't follow automatically from the rules.

[@pianissimo7121]

@@RichSmith77 it kinda does. If 1 isn't in cell 1 in box 1 then the 1 in row or column 1 from box 2 or box 4 respectively will have to be a knights move away from box1 1. This means box1 1 is following 2 rules which is illegal, so the only way it can satisfy a single rule is if it's in box1 cell 1

[@RichSmith77]

@@pianissimo7121 Sorry, I must be being slow. Why can't the 1 in row 1 be in box 4 and be a knight's move away from a 1 in box 7 (or vice versa)?

[@Jagnathbaba]

What I like about this puzzle is the fact that the conditions are relatively easy to understand but you have to keep thinking about its implications on different positions in the sudoku. Like, how you started with a 5 in the center, then went to the corners and then went to the middle cells etc. You basically keep discovering new things which is amazing.

[@darthrainbows]

Brilliant puzzle! I had a devil of a time getting the break in, but once I figured it out, the solve was very satisfying.

[@thomasstubtoft2544]

the way to logic the 5s away from the corners is to think of a cell next to the corner, ie. r1c2. Either it is a 5, which would prevent the corner from being 5, or it is not a 5, moving the 5s in the middleboxes to the edge by kingsmove, and again preventing 5s in the corners. Once I saw this and Simon did not, I could not keep watching as my yelling at the screen became to loud :) .... an skipping to the end, of cause Simon, master solver as he is, found another way.

[@PeterFreese]

Right - this would have immediately given him all 4 corners for 1,3,7,9.

[@LarkyLuna]

I was trying to set a "digits see themselves on knights moves" sudoku on my free time This will be inspirational lol

[@BanaiFeldstein]

If you stick with the fives at the beginning, plus look at those cells where there's only one place to put a number a knight's move away, you can figure out that five can't go in any corners because they have nowhere to go in other boxes, the stuff he got to somewhere in the 40-50 minute section.

[@DominikWegerle]

That was my thinking as well, but i'm not shure if that can be logically deducted. He mentioned it at 13:35 and then never ever got back to this restriction.

[@fynnsternis6432]

i love negative constraints like that but they are usually the hardest because you have to think so much differently

[@mike1024.]

I love the way this puzzle starts right off the bat.

[@derekswager]

at about 50 minutes into the video I noticed the 10's compliment rotational symmetry

[@longwaytotipperary]

Oh yay! Foggy puzzle!!! Recovering from nasty virus watching all my favorite KZbins and eating ice cream!! Feeling much better!!

[@JakeRoeder]

It would have taken me DECADES to come to the conclusions that Simon needed to move forward after recognizing the corner constraints. But, man, was that ever the most brilliant deduction! Well played, Die Hard, well played.

[@jrparker811]

This is an incredible work of art. A beautiful puzzle. Everyone should give it a go. There are logical conclusions on the placement of digits just from the rule set. Then the fog starts to lift.

[@studgerbil9081]

No idea why this was rated so low. The ten digits were hardly given since they were obscured. The break in "5" was easy but nothing else was easy at all.

[@nightmotherasmr]

I don't understand any of this, but I love how happy Simon is when he figures something out :) I just watch for the positivity.

[@matthiasvancampen3770]

I think I might've overanalyzed it today. But you can now from the very bezinning (after putting the 5) that the corners are 1,3,7,9. Take a look at box 2 for example: the 3 bottom digits AND the central digit need to make an appearance in row 1. However as the central 5 sees all of these and they either rescue a number from row 1 (r1c3 or r1c7) or they must be special. Since two digits of this 4-some need to be special, you know they're the 1 and the 3 in row 1 that don't need to be 'rescued'. By symmetry 1 and 7 appears in column 1 and don't need ti be rescued. Therefore 1 is in the top left cell of box 1.

[@cinny.]

This whole puzzle is really easy, actually. When you find 1 number, you immediately find another number. each number on opposite sides of the board (opposite sides of a line from bottom left to top right) add up to 10. Im pretty sure(?) this is correct

[@brunomcleod]

1:07:49 the subtitles interpret the f and the d (the frequencies of the other notes likely come into it) as the word "thank" and "you"! That's awesome

[@stephenleow9876]

I spotted some faulty logic that gave a 2 early at: 29:00 A 2 in the middle of Box 2 is NOT in its own box; it's in square 5 of box 2. I believe the correct logic would be to get the 2 in box 9 first, then once you have the 2s in columns 3 and 7 you can properly get the 2 in column 5 and go from there.

[@escapedlunatic27]

I did solve this eventually, but there were a couple of points at which I had to "cheat" by guessing. Fascinating to see the deductions Simon made which I missed - but even more so that such a puzzle can exist at all. It seems amazing that just those conditions, and the specification that (except for the centre cell) they're mutually exclusive, can not only lead to a unique solution but make it possible to deduce. Kudos to the composer.

[@lin-ni2885]

there was nothing more infuriating than having you have eight sevens and then just moving on to another digit

[@charliecarrot]

This is an amazing puzzle! Such a joy to watch

[@cerebralcomics]

Halfway through the puzzle, but its already very amazing!

[@Mennoo_]

I remember this one while it was still up for testing in the CtC Discord server. Unfortunately it had some issues with pencilmarking foggy cells, where given digits in the fog couldn't be pencilmarked. Lucky that issue has been resolved by Sven. When I tested this, I made one assumption that the corner cells would be the box numbers, and was able to continue from there in the the version of the puzzle at that time had much more given digits in the corner boxes. Problem at that time was that a lot of pencilmarks would had to be eliminated by a suddenly revealed given digit. It's good to see that Die Hard significantly improved that process. The puzzle seems to flow much more natural now. Die Hard later explained in the discord server the method involving those digits against the middle of the centerbox' edges, but I didn't quite get it at that time. So thanks a lot for explaining that part so clearly. Only really good sudoku solvers would be able to deduce such logic. If you are able to put such logic in your puzzle, you deserve nothing but praise for that (and definitely more than a 74% rating). In my opinion, people shouldn't rate puzzles on LMD very low (unless it's obviously designed very badly). Even if you don't like the solving partly, there is always a part where you can at least admire the logic that went into the puzzle. Every puzzle on LMD is created by someone who spent time on it, and imo that should never be demotivated by a ridiculously low score. I saw it also with my first puzzle I posted on LMD (still my only one for now). It got to a point where it was rated very highly with 95%, but one 0%-rating dropped it to 90% (puzzle has 5* difficulty, so not many solvers, hence a bigger impact). And even tho he messaged me with reasoning and feedback which I do appreciate, I still believe that 0%-ratings would be irrationally low, and either 40%-ratings should be the lowests you should give for a puzzle for which you see time and effort has been put into it. Nevertheless. This puzzle and the solve path i've seen now deserves all the credits. Good job Die Hard!

[@HalfBakedLunatic]

Excellent! I have a few puzzles on Logic Masters Germany where I think the ratings have been unfairly stifled ... so I know how you feel!

[@austinsinger7565]

I had to start over because I got stuck. After watching a few more minutes of you, I realize I had the rules wrong. The second was way better. I finished it in 40:25. Yay it felt good to finished one. This is my first solved puzzle since watching you. Now I can go back to see how you solve yours. I learn doing the section b first really help.

[@Kradlum]

Incredible puzzle and solve!

[@justinfarmer8371]

Only Simon can get excited for the same logic in the same puzzle lol grate solve

[@kaistoffel92]

Amazing puzzle. I cant even fathom of how youd start to set a puzzle like this.

[@matthewbondi380]

I immediately made a mistake by assuming the corner 1, 3, 7, and 9 were givens like the center 5, overlooking that they could indeed be 5s and satisfy a condition. I was correct, but didn't notice my overreach until after I cleared the fog :(

[@IBAndreas]

I made exactly this same error by first placing the 5 and then placing 1 in 1,1 2 in 2,2 3 in 3,3 etc. However, even though I totally neglected the possibility of 5 being a digit the fog was indeed revealed now in every single box and made for an easier solve. I didnt even realize the error of my reasoning until AFTER solving and then watching Simons solve and scrolling down for this comment. I can totally understand the easy ratings on LMD. I would have rated this a 2 and just assumed my (lucky) solve path was correctly reasoned.

[@Antiknight]

I really liked the second step in this puzzle! I think it deserves a higher rating.

[@FirstRecords204]

this is the first video on this channel i've ever watched where i actually figured something out before simon (the center digit must be 5) and got to feel smart about it

[@rizka7945]

Interesting how you can start the puzzle with (at least) two different logics: 1) Simon argues that for the center cell to fulfill two conditions it has to be a 5. 2) My argument was that the 5 in the center box automatically fulfills at least two conditions so it has to go the center cell.

[@gogogo123454321]

That's the same logic.

[@steve470]

@@gogogo123454321 "There's only one digit that can be placed in the central cell" and "There's only one place 5 can go in box five" are not the same logic.

[@mareksroka5629]

@@gogogo123454321not quite. One is saying that the center cell can ONLY be a 5. ("what are the option for that cell?") The second is saying that 5 can ONLY go in the center cell.("where can 5 goes in box 5?")

[@rizka7945]

@@gogogo123454321 It's the same conclusion through different means.

[@memyself8340]

From 13:31 to 14:50, Simon explains why his "5" pencil mark is removed from fows 2 & 8, and columns 2 & 8. Which then removes 5 as an option in the corners. Then at 20:05 to 20:20 he almost sees it again. I love it when I see a logic that he doesn't, but he always finds lots of ligic that I don't. Therefore, he always wins and I am entertained. Thank you Simon. (If you ever hear me yelling at the screen, just remember that I have time to scan while you are doing the hard work.)

[@Mephistahpheles]

@40:00 Simon gets the 2 which was my first digit. I used the "2 in it's own box" which forces the 2 in box 1 to be paired with a 2 in box 4. That quickly leads to the 2 in box 9. And that's the end of my "brilliance". Didn't get far in the puzzle at all. I was somewhat surprised Simon didn't pick it up immediately after the "naked 9". The two 2's in rows 6 & 7 force it, as well.

[@wojciechpietrzak1981]

I liked it very much how some of the logic steps synergized with my chess knowledge and experience. I mean: denying the possible digits seeing each other by a knight's move due to sudoku row or column logic is the same as trapping a knight with a rook in a game of chess.

[@PeterFreese]

I kept shouting at the screen that the 5's had to be on the outer edges of boxes 2, 4, 6, and 8, because they were blocked by knight's move by the cells directly adjacent to the 4 corners. That would have jumped you along much more quickly to getting all the 1-9s in their own boxes, but you found other ways to make it work. :)

[@lex1fy]

painful how simon realised so early that the bottom right HAD to be a 9 but didn't place it until 46 minutes in

[@MikeMJPMUNCH]

I'm confused by the rule set as it says "Each digit satisfies only one of the following conditions" but there are a few numbers that are both a chess knight's move away and in normal reading order.

[@RichSmith77]

"in reading order" just means the boxes are numbered left to right, top to bottom, so 1 2 3 4 5 6 7 8 9 Condition 2 is met by any digit in its box number, e.g. the 9 in box 9 (the box in the bottom right).

[@TeamCykelhold]

@@RichSmith77 yes and plenty of them are and satsified more than one condition since they are ALSO a knights move away from itself. Look at number 2 in the fourth box.

[@RichSmith77]

​@@TeamCykelholdThat's only satisfying condition (a), namely it's a knight's move away from another 2. It fails (b) as it's in box 4, not box 2. It fails (c) as it's not a 5. So it satisfies exactly one of the three conditions. The position within a box is irrelevant. The boxes (not cell positions) are numbered according to reading order. Box 2 is the top middle box. Only a 2 in box 2 has to avoid being a knight's move away from another 2.

[@TeamCykelhold]

@@RichSmith77 Aah ok I see. Thanks.

[@vananything]

This is easily in my top 5 of puzzles featured on this channel. (Top 3, maybe?) It one of those ones where it feels like there's some fundamental mathematical principle to it that's just out of my grasp… it must have been invigorating to discover when setting!

[@jasonmetcalfe4695]

Magic square logic at its finest I'm amazed Simon didn't spot it and go over it for people once again

[@MeanderingMikesManCave]

Fascinating puzzle!

[@rustypotatoes]

I love simons mini heart attack at the end 😂❤

[@peterhowitt3861]

I was totally baffled by Simon's logic path on this one, unless I completely misread the rule which I don't think I did.

[@ariel_haymarket]

this puzzle is horrendous - I love it

[@mrjohnnypinkpants]

really hard, and I got stuck about half way through. However I did manage to reason that the corners couldn't contain 5s, due to the pressure on the cells adjacent to the corners. Very proud moment for me!

[@lucaspromero6926]

THAT WAS SO AWESOME WOOOO GREAT VID AND SOLVE

[@NightChime]

1:00:59 - A tidbit of logic I enjoyed here in box 9 with the 146s, is that because the grey digits can't be 6, there must be a 6 between red and green. Take that to box 8, and the orange digit is 14. Granted, I don't recall if that does a whole lot, but it's a fun little extrapolation.

[@ArseneMichiels]

Hey! This was a fantastic puzzle. I was surprized when i saw the video because you didn't need to use the same start as I did (except for the five, obviousely). I started by proving, I think, that the corners needed to be digit of the box (n in box n). Because if let's say (1;1) is a 5, then either (2;4) or (2;6) is a five which means either (1;2) or (1;8) is the number of the box (because it only sees a 5). It can't be (1;8) because it would force (1;9) to be a 5 wich would break the sudoku. so (1;1) being a 5 would imply (2;4) being a 5 and (1;2) being 1. Repeating this vertically would then imply for the same reason (2;1) being 1whicl leads to a contradiction. By symmetry, I could immediately write the four corners. I was so prowd of this and I am amazed that it was not needed. Sorry for my pour englich. I hope this is understandable ;)

[@wolfmoon5720]

Funnily enough each digit being in its own position within its own box was how I initially understood the condition in the rules. Felt silly when I saw how Simon interpreted it so it was nice to see they did follow what I was originally thinking as well!

[@Gnarlf]

Fog puzzles are always ver interesting, but this one has a very wacky ruleset on top, wich makes it a blast

[@Myclutchisgone]

Very interesting puzzle! Realizing the positions of the couples (1, 9), (2, 8), (3, 7) and (4, 6) are specular makes it easier

[@rectrlgaming]

don't know if anyone noticed this but there is a flaw in the rules , that is the five in the middle box (5) either satisfy three conditions if its in the center or two if its not and that is not allowed.

[@epylar2]

Two is allowed

[@rectrlgaming]

@@epylar2 but three?

[@user-cz1qb8zt2h]

I've been doing sudoku (at best to average level) for years without knowing there was an 'adjaceny' rule........... Doh! Came across this site yesterday & this puzzle today. Made good progress on this one by learning that u gotta read the rules, CAREFULLY. Onwards & upwards.

[@danielepicone1480]

I tried this puzzle myself and the second digit I got was r3c7, which to my surprise was a given digit and hence did not reveal any fog! I think this bug is part of the reasons why it has such low rating.

[@chrystalic]

I was actually able to solve this one without your help. I have come a long way since I started watching you :)

[@andilee3537]

I think the rating is about right. It has a fascinating break-in the early part to clear some fog is full of discovery, but eventually it just descends into a horrible morass that has no clear path through it. A great idea that had a terrible ending. I got so bored i gave up shortly after clearing all the fog.

[@Lifeheart]

I love watching Simon seem baffled when things are solved by sudoku after doing complicated logic. Like he's dropping out of warp 🤣