Normal Sudoku Rules MOSTLY Apply!?

** TODAY'S PUZZLE **
Well, what can we say about this one... it's quite mad and utterly beguiling! It's called Killer Shikoku and it's the work of the_cogito. The rules completely flummox Simon but can you make sense of them? Give it a try at the link below:
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Rules:
Normal sudoku rules mostly apply; however the grid contains no 5s. Instead every row, column and box has a single repeated digit. (NB Beware! This does NOT mean that you could find nine cells in which 5s could be placed to make a genuine grid!) Additionally: divide the grid into rectangular regions of orthogonally connected cells. Each rectangle contains exactly one circle. A single cell with a circle counts as a 1x1 rectangle. A number in a circle represents how many cells are in the rectangle the circle belongs to. Rectangles cannot overlap. Every cell in the grid is part of a rectangle. Digits may not repeat in a rectangle.
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[@the_cogito5170]

The_cogito here. Really well done to Simon, I could tell you weren't sure if you'd broken the puzzle or not partway through, but you did great. I'm sure it's not hard to imagine that setting this puzzle was difficult lol, it's brainbending through and through. Thanks so much for another feature, this so far has been one of my proudest puzzles, I loved watching this, and am extremely grateful

[@cbear7996]

gorgeous puzzle!!

[@yvaskhmir]

This puzzle's ruleset looks like someone just finished a very hard puzzle with the rule that no two orthogonally connected digits can sum to 5 or 10 and developed a hatred of 5-s. But it's absolutely magnificent. And 5-s are overrated.

[@etienneschramm83]

I LOVED this puzzle! It made me feel really stupid at times, but I finally managed to find the solution. It took me about two hours and a half. I am amazed I managed to go all the way without making a mistake. I really had to double check every small deduction. I can't begin to imagine what a nightmare the setting must have been!

[@martinbull-gundersen8878]

Thank you so much for this puzzle! It's probably the funniest puzzle I've solved this year. It really never gives in, but its also not extremely difficult (more mind bending and forcing you to "unlearn" a lot of standard sudoku techniques). Also fantastic solve by Simon. Must admit I''ve been hoping for him solving this :-)

[@the_cogito5170]

@@yvaskhmir Haha zetamath made an open challenge for setters to set a sudoku with no 5s in it, and left it for us to interpret that how we want. It's a running joke that zeta thinks 5s are boring :P I'm really glad you enjoyed it.

[@roryparle]

Really interesting ruleset. It seems to be tricky to remember that doubles aren't allowed in the cages even though they're expected in the rows, columns and boxes.

[@jeffreylantz546]

I don't think the logic at 46:10 was sufficient to show the 6 in r7c3 had to go up, because the green 6/8 in r4c7 could've gone right, with 2 in r2c9, 2 in r3c9, and 4 in r5c9. A supremely confusing rule set, but trying to second guess Simon at every deduction made me feel like I somewhat understood what was going on. A fantastic solve! EDIT: Just realized you can't do that because it puts double 6 in the red region, but Simon didn't use that so I still feel justified.

[@stegra5960]

Yes. I agree with you completely. I spotted the same flawed logic and he didn't use the two 6s in one region as a reason for dismissing it. Pleased I saw your comment before posting myself as I hadn't noticed that.

[@Croccifixo]

I was actually coming to the comment section to mention that although the logic was flawed at that part, the conclusion was correct if he had considered the implication on the red rectangle having 2 6s instead. I had considered this when looking at if r6c3 could be in the rectangle belonging to r6c8, concluded that then that rectangle had to be a 7 and go all the way to the edge, otherwise it would repeat a 6, so the implication that the red rectangle was limited from taking column 9 meant r6c3 had to go up.

[@jimmyh2137]

This doesn't work because R7C9 can't be reached by any circle.

[@lewsouth1539]

I just posted my own comment about this very issue.🤪 He quite put the cart before the horse.

[@RichSmith77]

@@jimmyh2137 r7c9 would be reached by the circle in r5c9. It doesn't work for reasons others have mentioned (repeated 6 in red).

[@koegerli]

Simon: I refuse to pencil mark cells with 5 or more options! the_cogito: Challenge accepted 😏

[@rowanbrown5541]

I love that toward the end you forget that Shikaku's can't repeat and start proving solely via doubles already existing

[@aesheronanglvd3th309]

The 2-4 pair in the purple shukaku had me internally screaming for ages.

[@alexandraritter3542]

It was really difficult to keep all the rules in mind at any one time, and I think we'll likely each favor some over others. I often saw things that were different from his path in this one.

[@bramdesmit1196]

The sigh of relief that escaped me when you disambiguated the 6/7 in the middle of box 7 at 1:11:10 after I had been staring at it for 15 minutes! Sometimes you really miss some simple clues, but since trying some of the puzzles on this channel I’ve learned that that’s just your brain going blind lol. Really loving the content, it opened up a whole new world of sudoku’s for me. Keep it up!!

[@KaiSteinbach]

LOL ... available since 44:36 ... almost half an hour. :) But would it have helped logic elsewhere?

[@UnGeekCommeUnAutre]

don't talk about the 1 in row 9... eliminated at 1:02:00 while sitting there in the box with the other 1 for at least 1/2h .... ;D and this poor 2 in column 7 that is just asking (crying in fact) to be freed from the 9 since he place the 9 on top row.... painful ahaha

[@PuzzleQodec]

This puzzle is brilliant. Really happy this got featured!

[@dkosmari]

It's so funny to see Simon declare the Shikaku rule to be the easiest one to use, and then forget about it 5 seconds later. He spent most of his mental energy trying to not do Sudoku.

[@leojs5673]

Watching for the first time from my very own first ever apartment as I start college this week 🤓 thanks for keeping me company through the craziness of moving away, Simon and Mark

[@HunterJE]

Another way to look at the rule Simon struggled with at the start is to note that e.g. a digit repeating in its column does not necessarily mean either of the instances must also be the repeat in its respective row and box, which would be the case if it were just substituting out the 5 positions in a valid grid...

[@guitartailor]

Had to think about that for a second but I think you're right! Quite simple put that way

[@andersosterholm2538]

This is a wonderful puzzle! I love when there is some crazy rule forcing you to think in weird ways. And well done Simon, I think you did a great job.

[@David_K_Booth]

When I first found myself thinking "ah, there's a 1-2-3-4 quintuple in row 9" I got a fit of the giggles. Brilliant puzzle although not easy.

[@SamThe42nd]

I love how ridiculouss some of these puzzles are getting. I'd never be able to solve them myself but love watching you explain them. Keep up the great work!

[@cbear7996]

i’ve been having a really rough week, and this really brightened my day

[@dudbike]

I hope this week gets better for you! I hope spring has spring where you are and you can enjoy the spring flowers and birds!

[@devinpelech]

This would have gone smoother for Simon if he always remembered digits can't repeat in rectangles/shikokus lol

[@cbear7996]

“I know that you all completely understood it” actually, for the first time, i did completely understand it, and i feel proud of myself

[@markp7262]

51:46 finish. Absolutely brilliant puzzle. I would love to see more of the "sudoku rules mostly apply" ruleset. It can be difficult to follow along sometimes, but when it's over you know you accomplished something.

[@briancaster2876]

I want to see another Schrodingers sudoku, that one was so much fun to watch.

[@inspiringsand123]

Rules: 02:03 Let's Get Cracking: 08:44 What about this video's Top Tier Simarkisms?! Bobbins: 1x (51:26) Knowledge Bomb: 1x (18:39) And how about this video's Simarkisms?! Ah: 22x (14:54, 18:33, 20:12, 20:29, 20:29, 22:24, 26:09, 26:10, 27:12, 27:30, 28:02, 36:02, 41:08, 43:34, 46:36, 50:35, 52:40, 54:33, 59:07, 1:00:44, 1:05:12, 1:09:36) Hang On: 6x (02:07, 05:25, 05:31, 54:50, 59:37, 1:09:25) Sorry: 5x (45:01, 48:58, 55:59, 56:01, 1:09:48) Beautiful: 5x (28:07, 28:11, 30:51, 35:07, 47:27) What Does This Mean?: 4x (15:19, 44:50, 1:01:04, 1:03:04) What on Earth: 3x (27:36, 27:42, 1:14:13) Ridiculous: 3x (17:55, 1:08:45, 1:13:14) Wow: 3x (23:42, 23:42, 1:03:10) Good Grief: 2x (30:53, 58:21) Goodness: 2x (12:22, 1:15:08) Nonsense: 2x (17:37, 17:44) Extraordinary: 2x (01:00, 01:31) In Fact: 2x (11:47, 19:54) Apologies: 1x (00:17) Clever: 1x (52:54) Naughty: 1x (41:20) Lovely: 1x (31:02) Break the Puzzle: 1x (10:18) Fascinating: 1x (1:15:50) Incredible: 1x (01:43) Barbaric: 1x (1:04:21) Disconcerting: 1x (56:19) Our old Friend Sudoku: 1x (20:29) By Sudoku: 1x (08:48) Of All Things: 1x (56:31) Flummoxed: 1x (00:46) Bizarre: 1x (1:15:46) I've Got It!: 1x (52:40) Obviously: 1x (34:41) Progress: 1x (42:35) Juxtaposition: 1x (45:39) Pencil Mark/mark: 1x (11:02) Most popular number(>9), digit and colour this video: Ten (2 mentions) Two (158 mentions) Green (9 mentions) Antithesis Battles: Low (3) - High (2) Even (4) - Odd (0) FAQ: Q1: You missed something! A1: That could very well be the case! Human speech can be hard to understand for computers like me! Point out the ones that I missed and maybe I'll learn! Q2: Can you do this for another channel? A2: I've been thinking about that and wrote some code to make that possible. Let me know which channel you think would be a good fit!

[@eve_the_eevee_rh]

The rules were actually at 2:03 or 2:04, the time you mentioned, although Simon did say "rules", he did not further go on about the rest of the rules.

[@inspiringsand123]

@@eve_the_eevee_rh Thanks!

[@coralfeatherstone7019]

I would love to see an end-of-year summary of the puzzles ranked as having the highest of each Simarkism. 😆😄

[@jillwalker5206]

I feel like I need how many times he said “mental”

[@AexisRai]

The "Shikoku" here is probably a portmanteau of Shikaku and Sudoku, since their rules are being merged. [Shikoku (四国) is the smallest of the four islands of Japan, and shikoku (市国) means "city-state (e.g. Vatican)", but neither of those have bearing here.]

[@emilyscloset2648]

4 country checks out then xD

[@centroid41]

I'm always impressed with how fast Simon (and Mark of course) adapts to the new logic in "non-traditional" sudoku puzzles. My brain was definitely taking some extra time to warm up to the rule set :)

[@originalelijah9541]

I remember test solving this puzzle and I absolutely loved it! I’m so glad it got featured on the channel! Amazing stuff!

[@tyfunk8614]

Well that was total insanity, it's so hard to adjust your logic to all the different rules. Great solve, super fun to watch, and shorter than I thought it would be! Good on you for not getting stuck haha. Really hoping to see some streams from you guys soon! "Please don't touch anything 3D" would be great to watch!

[@kevinmartin7760]

1:07:47 Eliminating the 6 from R1C6 seems unjustified (though turns out to be correct). The double digit has not been identified in any of row 1, column 6, or box 2, and the rectangle does not contain any other forced 6. Simon says "which we've just seen can't go there" but I don't recall seeing any such thing. Even eliminating the 1/6 from R1C5 he only really seemed to half realize that the he had the double 7 in column 5 to justify that, since he just "noticed" the double 7 when he observed that means the 2/4 pair was a genuine pair. Perhaps the valid removal of the 6 in R1C5 was incorrectly echoed as validating removal of the 6 from R1C6. Or maybe I'm missing something...

[@dsquirrel]

Yes it was unjustified but he didn’t use it - concluded independently later that the cell had to be a 1

[@ozlich]

Agreed, came here thinking the same thing - luckily he didn’t use it and it didn’t break anything.

[@HeyRa131]

Sudoku habits are tough to break I guess.

[@ozlich]

@@HeyRa131 Yeah absolutely understandable, what a mind bending puzzle!

[@KaiSteinbach]

Well done, Simon. I was wishing that we could have multiple layers of different colour markings - almost like the Photoshop layers. Imagine you could give these layers names, and then use one layer for duplicate in row markings, another layer for duplicate in column, a third possibly for duplicate in traditional 3x3 box. That would be a software enhancement. A constructive tip I have, that does not require a software release is to "release" colours more frequently. Often, you either keep colours till the end, or even apply them to areas where the colour is only aesthetic (for completeness) but no longer for puzzle solving. Instead, sometimes colours could be reviewed, as in "do I still need this colour to conclude logic elsewhere?" - and if the answer is no, remove it. In this particular puzzle, I would have prefered 2 or 3 colours for marking line / row / 3x3 duplicates, possibly a 4th colour to mark circles which are done.

[@e7diablo]

Simon: I must not forget to focus on the shikoku/circles and not attempt sudoku Simon: [immediately focuses on sudoku]

[@crashtextdummie]

"That might be real, or it might not be real. In the sense that one of those digits might be wrong." This is already my favorite video ever in terms of quotability, and I'm only 24 minutes in.

[@Alsadius]

I feel like the right marking style for this puzzle might be three colours to mark off the doubles - one for row, one for column, and one for box. Having your doubles properly marked seems like it'd help immensely.

[@darleneofthetallpines5742]

This puzzle and this solve are so very entertaining! The time just flies by!

[@HunterJE]

Finally, back to being able to watch Simon videos on my lunch break on weekdays!

[@jamesackerman7473]

This is the first time that I have ever been ahead of Simon multiple times throughout. Apparently this rule set really worked with how my brain works. Most of the time I'm miles behind haha! Really cool puzzle!

[@Wecoc1]

Simon... Shikoku = Shikaku + Sudoku [Insert here a joke about how this is like his Sudoku scanning]

[@bezowee]

I want to make comment like that and I was thinking about the joke then I saw this😂

[@PauxloE]

Finally a puzzle where the Secret doesn't apply!

[@Nathan511]

I love how normal sudoku rules don’t apply in this one. I think Simon is so used to normal rules, he just can’t help almost falling into those habits. Very fun to watch.

[@MattGriffiths81]

What a puzzle, and what a solve. Switching between looking at rows, columns, boxes, and shikakus was an interesting task in itself. Every time you had to reassess what the rules for that particular thing were.

[@EelcoWind]

Loved it, took me little over an hour and a half, but never frustrated and nice logic all-round!

[@juliusenderling3902]

That's how a sunday should end!

[@emilywilliams3237]

I did not notice the time passing ... no chance at all that I will give this one a go, but definitely enjoyed seeing you work it through and come to a successful conclusion, Simon.

[@bodemeister118]

How Simon or anyone can navigate through this puzzle without making a mistake is quite remarkable. I'm a pretty good solver and made a couple goofs on this one.

[@jongarrett2388]

Took me 4 hours (11pm - 3am!) but happy to say I completed it. The disappointment when I got the "uh that doesn't look right" message turned to relief on watching the end of your video...

[@martinbull-gundersen8878]

Oh. Looking really forward to watch this. It is a fantastic puzzle! I really understand Mark's "change" in the rules, it could've spared me quite some time when I solved it :-)

[@kordellcurl7559]

What you could do is put a grey flash on the repeated digits. Technically to check you could whiten the grid and use the checker because it would show the wrong digits either way. (In which should be 1)

[@Laurana07]

I'm so happy with myself for solving this. It took a while, but time flies when you are having fun!

[@alibaageel9731]

The lower pink box really bugged me because it is obviously a 2 not a 4 since there cannot be two 4s in the same shikoku😂🤦🏽‍♂️

[@stegra5960]

Me too. And in the end he still didn't notice that and placed it by different means.

[@PauxloE]

I approached this from the Shikako angle, trying to color every region, with partial colors where multiple options are possible. There are not enough colors for this if you don't want to resort to the grays. Then I pencil-marked in the options for each circle (unfortunately it took me a while to realize that 9 and 5 are out), and start to notice triples/quadruples/quintuples allowing to pencil-mark more. And then slowly wittling away on the options. At some point I had to resort to logic like "in these two rows we have at most 6 digits 6 and 8, and we have 7 candidates, so one of them must be somewhere else". At minute 270, I got a almost fully filled grid, with two 47 and 46 pairs left (in row 1 and row 7), which just couldn't be resolved. After activating the checker, I found that there was an additional duplicate 9 (in r6c9), which I did put in instead of eliminating it earlier, so I used undo for like 30 steps, filled the 7 in correctly, and succeeded from there on.

[@ruokothyan7658]

Simon: this is good, i have two 8s in the collum. Me: 😂 never thought this day would come ...

[@albertsandberg]

Great work Simon. Never excuse yourself for your thinking time nor do never jumpcut it. It gives us mere mortals a chance to catch up and find something too and makes it interesting to watch how long time it takes.

[@th.nd.r]

r6c3 frustrated me to no end ngl lol. It’s in the same purple region as the 4 so it can’t be a 4! But for real great video, great solve, great setting, love the ruleset, the_cogito is so brilliant, and I do like these kind of puzzles that mess with normal sudoku rules on the channel, because I know Simon will always find the solution but there will be those entertaining moments of brain breakage every now and there lol. So yes I like this sort of thing and want to see more of it, well done, thank y’all for being awesome💙

[@ronjohnson6916]

Mind blowing. As long as I use Simon to get the basic grid I could make the little minor deductions with a lot of coloring. But yeah so tough to stop the sudoku "eliminations" that aren't valid. Wonderful solve that plays to Simon's real strength -- adapting to rules variations.

[@peterstromberg9614]

From now on one of my favorite sudoku puzzles.

[@Megatron9000]

25 minutes in and I am so invested in this solve. I love this rule set!

[@956675]

That was so much fun to watch. Can't say more than that or I would go on forever. Instant favourite.

[@anwenroberts7887]

This feels like a sudoku you would solve in Alice and Wonderland. Great job solving! It definitely hurt my brain trying to think about it.

[@soulbound11]

Spectacular! This one really threw me for a loop. Proud i was able to finish it. Took a couple hours though...

[@3Jeroen3]

After an hour Simon forgets that digits can’t repeat in a cage

[@wydadiyoun]

I miraculously managed to solve it without contradiction! for some reason I was almost sure I will have a contradiction but I didn't! great puzzle

[@Merione]

I feel that a slightly easier way to understand this ruleset is to take the repeating digits as an extra condition to check before performing an elimination. This means that whenever you're about to eliminate a pencilmark you must always ask yourself: "Do I have a repeat in this row/column/box already?" If yes, then you're allowed to eliminate the clue, if not, then you're not allowed to do it. This was extremely fun (to watch haha)

[@stevieinselby]

I was trying to think of a way to mark where cells were duplicated in rows, columns and boxes, but with digits potentially repeating in one, two or three dimensions it would be tricky, you would probably need different colours, eg 🟦 blue for boxes, 🟥 red for rows and 🟩 vert for vertical, but scanning it would probably be more confusing than without.

[@lydiagould3090]

Amazing, I couldnt have done it on my own but followed along while you solved it . Enjoyed the challenge!

[@sugarfrosted2005]

Now I've seen everything, a 1-2 triple!

[@NotCochon]

Running a terrible fever today and this video was exactly what I needed to distract myself for some time. Wonderful solve, Simon! Can't wait for the next one :)

[@DoongXiouHua]

45:43 r5c8 could be part of the green region, I think Simon is getting lucky there.

[@gpaciga]

Came to the comments to point this out too

[@ichtusvis]

If purple in r7 takes the stripe, then the red region in r6 will be forced to be of size six, leading to a repeated digit in that cage

[@LaytonBehelit]

True. Here's a reason why the purple stripe doesn't work. Red above purple would have to be a 6 which repeats a 6 in its rectangle.

[@karlmortenlunna2417]

Yes, it was bad logic at that point. But the purple region couldn't be a stripe, because r6c3 would be taken by the region starting in r6c8. At that region would be a 7-cell region because it couldn't repeat the 6 in its region. And that isolates r7c9.

[@RichSmith77]

I don't know which I find more annoying. That Simon made the mistake, or that I didn't realise it was a mistake when he did it and just accepted his reasoning. Glad someone was paying attention.

[@Keyboardje]

It helped me to give every confirmed double an extra colour flash so they were easy to spot, so I didn't have to constantly search them again.

[@thommy4078]

Took me 80minutes. I had a hard start (forgot about the "no 5 rule"). It was a really tough but approchable puzzle. I really enjoyed it and im happy that i solved a "+ 1hour Simon"-Puzzle.

[@GarionBoggod]

I found the distribution of repeated digits in the solution to be fascinating, I was expecting it to be more even. It's great that a couple digits were never used as repeats while others had multiple instances of being duplicated.

[@patrickdematosribeiro1845]

Incredible puzzle and solve. One small remark about checking the repeats at the end: Since there were no fives in the puzzle there had to be at least one repeat in every box, row and column. It would actually be necessary to check that there is no second repeat anywhere or in other words that there is at least one 1,2,3,4,6,7,8 and 9 in each box, row and column.

[@G.Aaron.Fisher]

First one in a long time that I've had to give up on and come back the next day. Glad I did, because rereading the rules it turned out I missed one! Much easier without digits repeating in rectangles.

[@Zuldaar]

Amazing puzzle, spent exactly 120 minutes, down to the 5th to last digit where it turned out that I had broken it at some point. Can't wait to watch Simon solve it and show me where I had my mistake

[@tehcanadianbacon314]

Whooo Hooo, finally finished this one. Had a pretty good time before I checked my work and realized I had 2 doubles in one row. Had to reset about 20 moves to find my mistake lol. Really cool puzzle and I got a lot of practice using some of the new tools :)

[@mikes.8647]

Maybe it would be more efficient if Simon used only the pen for the borders and then colored the shells that are "repeated" digits. It would be much easier to spot the "normal" digits! Either way, this puzzle was indescribably beautiful and mind bending, just WOW!

[@PauxloE]

56:10 "Please don't be obvious" Some easy things to see here (not sure whether they bring you much forward): → The purple 6-box has a 4 next to a 24 (which has another 24 above it, which removes the 4 from the vertical red 8-box) → Where does the 3 go in row 3? (in one of two places) → Where does the 1 go in row 6? (only one place) → Where does the 8 go in row 7? (one of two places) → Where does the 9 go in box 8? (One of 3 places, which has an impact on row 7, and the possible locations of the 9 in the horizontal red 8-box) → Box 7's duplicate is a 1 or 2 and there us a 6 in the box, so the 67 is resolved (which then has impact on the column). → Box 1's duplicate is a 1 or 2 and there are 7 and 8 in the box, so the 6789 pair gets reduced to a 69 pair (which has also a bit of impact on both columns, forcing two 8s into box 4).

[@Coyotek4]

59:21 ... I'm calling an under-an-hour solve as a 'win' for this one. Incredible puzzle!

[@guitartailor]

I think doing it quicker than the video has to count as a win!

[@RichSmith77]

I'd calling any solve a win on this beast. But under an hour is certainly impressive.

[@josephsugarmann6765]

I was going to suggest that Phistomephel make a hard-mode version of this puzzle, but then I remembered that his specialty is doing weird things with geometry

[@Zhon66]

I made an incorrect assumption relatively early that did not lead to contradictions for some time, and by the time I realized what it was, it was far too late to fix it and the puzzle was hopelessly broken. Still an enjoyable experience.

[@lewsouth1539]

Here's a handy rule to remember for this sort of puzzle: In any row of boxes, the repeated digits in the 3 boxes are the same as the repeated digits in the 3 rows crossing them; likewise for columns of boxes. I found this especially helpful toward the end of my solve.

[@paulanderson5704]

Till the whole end Simon couldn't feel the fact that he could apply sudoku in his coloured boxes.

[@menbah]

Quite unusual to actually see Simon struggle with a rule set, usually the scanning is the only thing holding him back. But not surprised this would be the one to do it, what a wonderful monster!

[@Jesthers]

Oh, I was able to finish this one as well! Always feels good to be able to beat a puzzle for once 😁

[@FleckerMan]

zetamath, who sets puzzles that have been featured here on CtC, has a lovely channel on youtube (zetamath does puzzles) where he regularly streams live solves, and chat can join in - it's great fun and I recommend subscribing - the extra relevance here is he did a 'fiveless challenge' recently and many setters sent in sudoku puzzles that didn't contain any 5's (in some meaning decided by the setter) - I missed part of the stream so this one may well have been featured or connected, or could be a coinkydink - in any case, highly recommended (and close to 1,000 subscribers :) :) )

[@hundehuegel]

I thought the same when I saw the rule set

[@Shade0130]

Zeta did in fact do this puzzle during one of his streams. Took him slightly less than 90 minutes.

[@pixllo]

Gosh that messed with my brain big time. I somehow didn't take notice of the rule about not repeating numbers in a rectangle which made my life so hard... but enough to figure out most of the half left rectangles. So I didn't feel like I was missing a rule lol. Very good puzzle

[@HunterJE]

33:45 I think a simpler way to reach the same result here is to realize that since you know there's a repeat in the yellows, anything outside the yellows must obey sudoku rules vis a vis the column. As such, the known 3 just eliminates the pencil-marked 3s in the yellow cells outright...

[@guitartailor]

Yes exactly. The three outside of yellow means you can't have a three in yellow

[@joeomundson]

I'm not sure that works...? Doesn't the 3 have to be included as a yellow? Otherwise it's a 1234 quadruple with a 3 outside, and the 3 could repeat. I think you have to think about the height of the rectangles Edit: Oh wait the 4 yellow cells must have a repeat because otherwise they would add up to at least 10 and it needs to be 9, I understand :)

[@Klimentovici]

I think it helps splitting the digits in the 1234 and 6789 quadruples. Then, wherever you see the quadruples transformed into quintuples, it means the doubled digit is in that sub-set and you can apply the normal Sudoku rules to the other sub-set.

[@fatercoelho7476]

I can hardly believe that I actually made one of this sudokus :D took me 4h but I'm so happy that I finally got one puzzle right :D

[@thithildeprouv8310]

I managed to solve it in a bit more than 1h30. I was a big challenge having to reconsider everything you know about sudokus. But I loved it, it was a great way to change my mind from my studies hihi

[@thehermit761]

It is always a pleasure to watch you do these puzzles both you guys are on another level. I myself have started some sudoku vids and live in London would love to meet up some time.

[@sakkikoyumikishi]

I believe there's an easier way to figure out the shape of the rectangle around circle (r7,c3) aorund 46:00. If it were a long line, then the only circle that can reach (r6,c3) would be the one in (r6,c8), as Simon says. However, to do that, it needs to contain either a 6 or a 7 (8 is impossible since it would either overlap with a rectangle on the left or cut off a section to the right). However, if it is a 6, it repeats a 6 in the rectangle (r6,c6), and if it is a seven, it cuts off the circle in (r7,c2). That circle could then be no bigger than 2. Since we know that it is actually a 4, both of those are impossible and thus the circle (r7,c3) must belong to a 2×3 rectangle.

[@gc2009able]

It took me about an hour and a half, and I had to back track *a lot*. I kept running into erroneous assumptions and errors! Once I worked past those glitches, and had a bit of a grasp on the rules, it was quite fun! I definitely rely on being able to check the video now and then for "sanity checks", though!

[@Ian_Hay]

Great, great solve of a mind-bending puzzle that I gave up on way too soon.

[@lewsouth1539]

At 45:29-45:50, Simon eliminates the possibility of the 1x6 rectangle in row 7 by noting, in part, that the only circle that can reach r5c8 is r5c9-but this is wrong: If r4c7 = 8, then it can reach it, and he hasn't ruled out this possibility yet. The real problem at this point is r6c8, which can't = 6, since that would put two 6's in the rectangle (which Simon notes later, but still before ruling out r4c7 = 8), so it would have to = 7 and extend to c9, isolating r7c9 as well as disallowing r4c7 = 8, etc.

[@stevieinselby]

Wow ... that puzzle was *insane* 🤪 ... I'm not surprised your head was fried!

[@SilviuBurcea1]

At 45:30, Simon forgets that R5C8 can join the green square and the 6 in row 7 can go horizontally.

[@randomuser2461]

56:08 Box 9's 8 rectangle requires the 7/9 to exist because of row 9. That rectangle has 5 optional numbers with 4 boxes left. That means 1 3 or 4 can't be in that box or row 8.

[@tremkl]

Wonderful solve of a wonderful puzzle. Don’t feel at all bad about taking your time on it, it was a rather maddening ruleset, and it was incredibly easy to make a false assumption and ruin the whole grid.

[@mute1085]

Spent over an hour struggling and squeezing slightest information from the puzzle... then I noticed that I forgot about the sneaky "Digits may not repeat in a rectangle." at the end, and it all fell into place so quickly

[@danielrhymer1762]

61:03 for me! Pleased with that one. Certainly gets easier trying to decipher the rules the more you do the puzzle but leads to some interesting logic

[@elizabethswann05]

when Simom got stuck in the 56th minute there where so many things to spot: the 69 pair in r2c12 because of the box, the 7 in r8c2 also because of the box and around 5 ninutes later the 2 in r7c7 because of the colum. (I am writing this because I'm kinda screaming at the screen right now which isn't helpful while trying to fall asleep which is what I'm trying rn; also I wanted to make clear that I have a lot of respect for Simon's sobbing skills. whenever I'm screaming at the screen I also remind myself that I would've never come this far and I'm absolutely amazed by the videos from this channel and so thankful for the opportunity so learn so much about (solving) Sudoku!)

[@elizabethswann05]

sorry I meant "Simon's solving Skills"

[@elfdogre2181]

Lovely puzzle. Full of 'Simon.exe stopped working' moments 😂

[@gingerscholar152]

around the 50:00 minute mark I was thinking delete the colors and assign 3 colors for the repeat in the row, column, and box

[@genevieve4679]

That was so much fun!

[@HidingAllTheWay]

3:06 the much simpler way to solve it was to realise that if you put a 3 in any of the yellow boxes you have a repeated digit and it becomes normal sudoku column, and as such the remaining yellow digits must be 1, 2, and 4, adding to 10 and breaking the puzzle.

[@sanabas1]

Excellent puzzle, definitely worth trying, and not as hard as the long ruleset or 75 min video imply.

[@cobalteclipse117]

I watched “normal sudoku rules cannot apply” yesterday, and now this appears today aha