How Can These Sudoku Rules Ever Work?

** THE SUDOKU EVENTS OF THE YEAR **
Phistomefel's first ever sudoku hunt is OUT!!! We've gifted it as a Christmas present to all our patrons to say "Thank you" for supporting us.
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/ crackingthecryptic
** TODAY'S PUZZLE **
Today Simon attempts a puzzle he's wanted to try for a while but has been slightly scared of given its reputation. It's called Numbered Regions, it's the work of the brilliant Jesper Josefsson and the ruleset is absolutely mad. How can this have a solution?!?! Let's see...
Play it at the link below:
app.crackingthecryptic.com/su...
Rules:
Divide the grid into regions, each consisting of nine orthogonally connected cells. Each row, column and region must contain the digits 1 to 9 once each. The digit in the top-left cell of a region (its leftmost cell in its highest row) is its “region number”. All region numbers are different. If a cell with the digit X in a region with the number N contains an arrow, then the cell X steps away in the indicated direction belongs to the region numbered N+1. Not all possible arrows are given.
** NEW CONTENT ON PATREON **
As well as the Phistomefel and Jay Dyer extravaganzas, Simon's solve of Magnus Josefsson's new puzzle Castle Wall Yin Yang #1 is now available as a bonus video. You can play the puzzle at the link below (and the logic-masters link contains an example):
app.crackingthecryptic.com/su...
logic-masters.de/Raetselporta...
Joining us on Patreon costs as little as $2 a month.
Remember that patrons gets access to their own special channel on the CtC Fan Discord server - where you can find hints ;)
/ crackingthecryptic
** NEW GAS PACK IS OUT **
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It's already out on Android and App Store. 60 original puzzles by Sam Cappleman-Lynes, Clover and Philip Newman!! Earn party hats and dinosaurs with these brand new puzzles!
We've also released a FREE app full of handmade puzzles to celebrate reaching 500k subscribers - simply download the Cracking The Cryptic app on Android, Steam or App Store and then select the 500k pack. We're streaming a playthrough of this app and you can watch all seven episodes
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[@stangerrits6712]

56:33 What a joy to have seen something that Simon didn’t yet see, and then watching it unfold to him, after which he says ‘now that’s very complicated’. Wonderful and original puzzle!

[@carterbrock7971]

I had the same experience! Don't know how I spotted it, but he got agonizingly close so many times.

[@jesperwillems_]

Thank you so much for featuring this puzzle, really liked your solve! the puzzle’s not mine or anything but the rules just state “Jesper” as their creator and when i saw this the first thing i thought was “huh i made this?” so now imma pretend i made it

[@Jablicek]

Lovely puzzle, very nice to solve! Thank you :)

[@glum_hippo]

good strategy

[@dwebb2805]

Dear Simon, this puzzle was pure artistry, and the video/solve equaled its beauty at every turn! You often malign yourself for missing things, or minimize your own genius by how you marvel at others' genius, but if there was no proof beforehand (spoilers, there was plenty) this is all anyone ever needs to say with no uncertainty that you are a special man, and not only are you capable of doing battle with these giants on a weekly (or more frequent) basis, but you do it while also bringing along the rest of us mere mortals for a ride! Every day this channel produces videos that are a treat for us viewers and lovers of logic, but this one certainly deserves a place among the pantheon of great CTC videos!

[@emilywilliams3237]

Very well said!

[@leojs5673]

it’s a very rainy chilly day among some weird political moments here in brazil, so there’s nothing i’d like better than cuddling up under a blanket with a nice long ctc video to keep me entertained. thanks simon! 🤩

[@isabelamacedobellsita8394]

O negócio ta complicado

[@davidmiller9485]

@@isabelamacedobellsita8394 Best of wishes to both of you. I read about the storming mobs last night.

[@mtbforever1]

Exatoooo!!

[@piarittersporn]

My best wishes to Brazil. May truth and justice finally prevail.... and also in the rest of the world.

[@longwaytotipperary]

We are also familiar with weird political moments here in the US 😳. I’m about to settle down with my blanket and 🍷and 🍿 to let Simon (and then Mark) entertain me. Also have University of Georgia (my alma mater) defend their title of national football champions on TV in background. Listening to Simon read the rules - oh my! 🤔

[@ryawood2789]

34:36 “Let’s make it orange for its sins” has me rolling😂

[@kimh6979]

This was a “watch and admire “ puzzle for me. So far out of my league but loved ❤ watching Simon! Thank you 😊

[@kindlin]

I actually saw the first couple moves before Simon, but it wouldn't take long for me to get lost. Not. Long. At. All.

[@RenameJames]

Simon: "I'm not really all that intelligent" Also Simon: *casually solves some of the hardest puzzles while on camera*

[@HunterJE]

If you're going to use two different shades of the same color (such as light versus dark green) using them in adjacent regions is actually the best case, if you can compare across a shared border it's pretty easy to tell they're different while trying to distinguish between non-adjacent areas of similar color it can be harder to be sure if they're different...

[@HunterJE]

As always the unfairest part of chaos puzzles is you feel like you've achieved something and then you have to solve a dang irregular sudoku ;)

[@marino1805]

For anyone else who might get discouraged trying out the puzzle while looking at solve time (1 hour+), give it half the time and see how far you get. This one is really great and the steps all flow smoothly along, atleast they did for me. Though i did make a blunder cause i got hasty towards the end and had to check up with Simon.

[@asbjrnfossmo1589]

Was it where the 3 had to go in the 3rd region? If so, I made the same error, but luckily that error was salvageable because it was pretty late in my solve.

[@chomikhunter]

1:29:18! This was an absolutely brilliant puzzle! I always love when Simon finds one of these sudoku-esque puzzles with bizarre rulesets, so thank you to Simon, and Jesper for creating such an amazing puzzle! This was a fantastic puzzle!

[@inspiringsand123]

Rules: 03:30 Let's Get Cracking: 08:07 Simon's time: 1h25m23s Puzzle Solved: 1:33:30 What about this video's Top Tier Simarkisms?! ​Scooby-Doo: 3x (24:23, 40:53, 45:41) Bobbins: 1x (1:27:33) Phistomefel: 1x (02:19) And how about this video's Simarkisms?! Hang On: 11x (18:19, 18:33, 33:01, 34:04, 36:46, 37:50, 37:50, 39:41, 51:20, 1:04:28, 1:21:13) Beautiful: 10x (18:19, 38:48, 38:51, 59:14, 59:14, 1:12:24, 1:23:44, 1:24:50, 1:33:53, 1:34:12) Ah: 10x (27:40, 28:37, 37:06, 44:32, 44:32, 50:40, 1:08:43, 1:11:12, 1:17:03, 1:17:09) By Sudoku: 7x (20:31, 1:17:28, 1:20:25, 1:24:14, 1:24:16, 1:24:22, 1:26:01) In Fact: 5x (17:09, 21:15, 42:05, 56:29, 1:29:12) Progress: 5x (11:50, 15:36, 31:51, 48:20, 53:34) Wow: 5x (25:44, 1:00:14, 1:30:50, 1:33:40, 1:33:40) What on Earth: 4x (22:31, 25:51, 27:51, 46:39) Naked Single: 4x (1:31:17, 1:32:16, 1:32:49, 1:33:12) Lovely: 4x (18:22, 18:22, 1:01:02, 1:29:15) Brilliant: 4x (01:16, 01:16, 53:43, 53:43) That's Huge: 4x (40:16, 1:23:21, 1:26:16, 1:30:43) Sorry: 3x (41:45, 1:19:30, 1:34:27) The Answer is: 3x (24:21, 1:16:40, 1:22:43) Clever: 3x (24:39, 54:59, 56:01) Incredible: 3x (01:26, 01:26, 07:59) Magnificent: 3x (01:56, 1:33:34, 1:33:59) Pencil Mark/mark: 3x (22:08, 1:16:32, 1:31:47) Good Grief: 2x (40:14, 58:26) Break the Puzzle: 2x (1:17:09, 1:17:11) Going Mad: 2x (10:40, 39:51) Obviously: 2x (34:06, 1:10:23) Intriguing: 2x (45:49, 1:17:55) Baffling: 2x (05:16, 05:20) What a Puzzle: 1x (1:33:40) I Have no Clue: 1x (54:06) Insane: 1x (1:26:56) Shouting: 1x (02:06) Epiphany: 1x (55:07) If I Trust my Pencil Marks: 1x (1:31:47) Stunning: 1x (1:34:16) We Can Do Better Than That: 1x (1:29:42) Phone is Buzzing: 1x (17:39) Plonk: 1x (1:22:17) Next Trick: 1x (1:31:14) What Does This Mean?: 1x (39:35) On the Cusp: 1x (1:25:01) Nature: 1x (38:57) Unique: 1x (01:07) Most popular number(>9), digit and colour this video: Eighteen (3 mentions) One (164 mentions) Green (83 mentions) Antithesis Battles: Even (3) - Odd (0) Higher (5) - Lower (0) Row (29) - Column (15) 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!

[@cleanse]

github

[@chikinnuggy]

bots are crazy these days

[@PhaythGaming]

“Look” should be there.

[@leonmanthey4512]

„Oh deer/dear“ don’t know how it is written

[@jeff21killersep54]

These bots are strange

[@climing8070]

God that logic about rows @ 1:20:00 was fascinating, I'd've never thought of anyhting like that. Marvelous work Simon, and thank you Jesper for the gorgeous puzzle!

[@th.nd.r]

That is utterly incredible and thoroughly entertaining. The fact that someone can create an hour and a half of logic and joy from a regionless grid and a somewhat sparse spattering of arrows… Just incredible. Brilliant setting and solving.

[@emilywilliams3237]

You love this sort of puzzle, and it shows, Simon. Thanks for this video (No apology necessary for its length ... )! Edited to add: you mentioned fatigue at one point as a factor in these long solves, and I can absolutely believe it. How you keep going at such a high level of effectiveness, even in a fascinating puzzle, is quite remarkable.

[@Gonzalo_Garcia_]

I already solved this one a couple of months ago. The ruleset was crazy, but the solvepath was absolutely fantastic from what I can recall. There's also a second version with a very similar idea but slightly different rules which was as good as this one, it would be great to see it featured on the channel as well.

[@nosy-cat]

I think Mark should get a chance to solve one of these beauties as well.

[@DoodleNoodle129]

Do you have a link for that other puzzle? Would love to give it a try, if it’s not too much harder than this one.

[@Gonzalo_Garcia_]

@@DoodleNoodle129 KZbin deletes comments with links on them, so unfortunately I can't share the puzzle that way. However, if you go to logic-masters and use the advanced search tool, it shouldn't be too hard to find the puzzle yourself. It has the same name as this one. I hope that helps, but feel free to ask me again if you still can't find it.

[@Alteram]

I tend to just watch along and try to figure stuff out as Simon solves, because I am not very fast when it comes to solving the sudoku parts, but the start of this one clicked with me, and solving the regions felt quite easy to me. There were times where I was like "obviously it can't be x, because..." and it made me feel good lol, still would have taken me like an hour to finish after getting the regions, so enjoyed watching your solve instead.

[@markp7262]

1:07:48 finish. Absolutely loved the logic on this. It started in the corner and then spread out from there, each piece of information adding on. I actually started pencil marking a bit earlier than Simon, before I had finished the bottom. It helped me to complete the 9 region by placing the 1 in the first column. Excellent puzzle!

[@NinjarioPicmin]

Wow this was absolutely incredible. It took me 140:41, but was worth it every single second, that was so elegant, i absolutely loved how it came together

[@trisha2584]

I love this type of puzzle, some parts I seem to see before Simon (which I get a lot of satisfaction from) and yet other parts that Simon sees easily I struggle with.

[@kehtabpeg]

Natural inaptitude for sudoku 🤣 Simon cracks me up

[@GQSmoos]

Unbelievably, I actually solved this one!! Time of 2 hours 20. I saw the row 3 break in right away and thought, “if I see the break in, maybe I can do it?” The regions actually came fairly easy. It was once I needed to start cleaning up the sudoku that I really struggled

[@victoriam6569]

Good job!! 👍

[@ericdimickeastman5127]

111:43 for me. I loved it. I'm terrible at irregular sudoku. This was super tricky to find the next step at points, but I always felt sure of what I marked into the puzzle. Quite something!!!

[@penningmeestercgkdelft9159]

1:08:18 Yes :-) In case of doubt, always re-use yellow!

[@nosy-cat]

Stunning puzzle. And I managed to solve it in almost exactly the same time as Simon. Of course, while solving, I didn't shoot a video explaining my thought process to thousands of viewers, so there's that... Thanks for bringing this jewel to us.

[@danielrhymer1762]

74:11 for me. Like these puzzles a lot because even though it takes a long time, I always seem to be progressing and rarely feel stuck 👍

[@DoodleNoodle129]

This has got to be one of the greatest puzzles I’ve had the pleasure of solving. Surprised myself by managing to solve it in under 70 minutes too. I’d recommend anyone try to give this one a shot, it’s an absolutely amazing time trying to solve it.

[@jonatanpersson82]

This sort of sudoku where you have to make the regions is probably my favorite soduko rule!

[@MaierFlorian]

56:20 when my 10 minute shouting finally reaches the past and he realizes where to look next :D fun to watch as always, thanks a lot!

[@olleicua]

I love puzzles like this. I usually start solving while watching and then pause the video whenever I have an idea. This one I did entirely on my own with the video paused at the beginning and as you say, I was quite pleased with myself! :)

[@Thorinbur]

100 minutes for me. It had a nice flow and sattisfying break in. Never trurly stuck just metodical progress. Loved it.

[@StephaneBura]

What a wonderful puzzle and solve. Bravo Jesper and Simon!

[@HunterJE]

I doubt it matters but not sure Simon was right around 10:00 to say the 1 could not possibly be its region's top left cell - if the region took r9c1-2 and r8c2-8, that's 9 cells, r8c2 is the leftmost cell of the uppermost row, and the region under it can get out up column 9

[@57thorns]

But I believe r8c8 actually prevents is with an arrow, as the 2 region would have to be 10 cells large.

[@HunterJE]

@@57thorns Yes, but that's not something Simon was looking at (or at least not something he mentioned) when making the general region geometry claim

[@RichSmith77]

Couldn't the second region pointed at (r9c3) also escape to the left and up column 1? There's no reason the 1 region had to take r9c2 to block it into the 16 cells Simon highlighted. [Edit: I think the arrow in r8c3 probably prevents this, as it would also have to point to the second region. But there's more to proving it than Simon alleged.]

[@57thorns]

@@RichSmith77 There is just about enough space for a region 2 to go around that way, but the arrow would have to be a 1 again, and that would not work. Well spotted.

[@iain_nakada]

1:20:07 Yes, yes it's extremely useful. 8 placed in green, 1 placed in domino in orange, 8 restricted to R1 in yellow, 8 removed from R7R9C9...

[@chitraagarwal8259]

The rules scared me off from trying this puzzle - there's no way i would have gotten through this, although surprisingly i did manage to catch a few deductions ahead of Simon. That i guess is the joy of watching this channel - those moments when you can think ahead of someone who is undoubtedly an absolute genius. Thank you Simon for giving us the chance to shout at you once in a while and hence feel good about ourselves. If you just breezed through these puzzles without getting stuck it would really make it a boring watch! Shouting at the screen is much more entertaining than gaping at genius :)

[@joelstevens5670]

In a word, spectacular! By far one of my favourite puzzles from the last few years watching cracking the cryptic, this was an absolute blast to solve. :)

[@piarittersporn]

I preferred to just passively enjoy this puzzle and watch Simon. Congratulation! My brain would certainly have gone on strike today.

[@wrathofnerds]

The logic that Simon found around the 40:00 mark was truly beautiful. Just....what a chain. Dastardly in creativeness but juuuuuust visible.

[@sophierw]

Thanks for an amazing puzzle solve! Always fun to watch. You really know sudoku and the whole community, thanks for bringing us into the sudoku world with you, it is great to feel a part of it!

[@davidblake6889]

What a brilliant puzzle, and rule set. Thanks to Jesper and Simon for some really cool logic. (Way out of my league, BTW). Love the long ones.

[@artursruseckis4242]

R1C1 was always pointing at orange as soon as you reduced region numbers to two possible digits. If it was 4, then it already falls on orange cell, if it was 5, then orange lose possibility to be a region#5 and becomes a six, which requires the yellow region point to it anyway. Thus the blue-yellow-orange-green-purple chain is established much quicker and then there is the challenge to map all yellow arrows onto orange region that is possible only in one particular way

[@komnsenz]

Late in the evening, I saw 1:35 and thought no, I'm not going to sit through anything that long. And here I am, an hour and a half later - amazed, impressed, and thoroughly entertained. Excellent, Simon. My brain hurts just from watching!

[@orosma868]

Absolutely wonderful puzzle and a brilliant solve from Simon, even his sudoku scanning skills kicked in at an impressive level! Pure joy to watch.

[@TheMeanAdmin]

I look at ruleset. I look at the video length. I look at the puzzle. I'm rooting for ya, Simon o/ Love long videos and this one looks mighty promising ^^

[@gweria]

95 minute video, 5/5 stars for difficulty, even Simon doesn't know where to start. Simon: "Do have a go."

[@glum_hippo]

Marvelous puzzle once again! GAH! And such an impressive solve from Simon.

[@mery1973able]

Absolutely brilliant puzzle. Loved it from start to finish.👍🙂

[@crystalgehrt8861]

Insane. Insane. I stayed up all night doing this. It's now 6am and I have had no sleep, but it's totally worth it.

[@victoriam6569]

Super fun!!! Thank you

[@rysia4669]

Just started watching, and found myself screaming at the screen: Nowhere does it say normal sudoku rules apply!

[@gamerbb2]

Loved this one. Amazing that it is even possible to set something like this.

[@ronschorr8974]

Took me 2 days and I had to spend an evening dreaming about it, but ultimately I got it done and I feel incredibly proud of the effort. What an amazing puzzle. Really bizarre concept and confused my brain for quite a while. Glad I stuck with it. Thanks so much for designing and sharing this with us all.

[@iain_nakada]

Well, I finally did it! A solve faster than Simon (85:51). :D After multiple years of trying. Lovely puzzle - I really enjoyed the region finding stage, the double arrows are eye-catching and give you a good idea where to start, then it all starts to come together when you get to the point of realising you're running out of region numbers. (Simon gets there around 50:40). The irregular sudoku felt a bit more clunky, I guess cos I'm not very good at them, but you just keep plugging away and it goes eventually.

[@MichaelMoore99]

The first thing I realized when reading the rules and seeing the example is that Region 9 will have no arrows in it, because there will not be a Region 10 to go to. And then when Simon mentioned the whole "arrows near edges" bit, the whole thing started to make sense, because I got to see some of the largest constraints of the puzzle's initial starting position. Simon pointed out that arrows can point at other arrows, but then I saw that arrows CANNOT point at EACH OTHER, so if the one he pointed out was indeed a 5, then the target could NOT be a 5 as well, and so forth. (Simon points this out a bit later with green and purple recursion.) This is a very wild puzzle and once it starts to unravel, it's glorious. One criticism I'd like to level at Simon is to try to use more color-blind friendly colors when making regions, because the purple and blue that he started with were "the same color" to my eyes, so it was hard to distinguish between them when they were orthogonally adjacent. (Certainly OK to use both colors, just not next to each other.) If you're reading this, Simon... 1. Thank you so very much for everything you do, but... 2. Even though it's impossible to get a list of all color-blind-friendly colors, because everyone is different and some are mutually exclusive, so you can only hit one or the other... the most common ones I would recommend avoiding being next to each other are: greens/reds, greens/browns, light greens/yellows, yellows/oranges, blues/purples. If you can avoid those 6 combinations, you'll likely be a benefit the vast majority of your color-blind viewers.

[@jimi02468]

That was the first thing that came to my mind also. That there must exist a region which has no arrows in it. Too bad it was pretty useless information when you're just starting the puzzle.

[@ServantOfSatania]

73:31 What a fun puzzle, I was staring at the grid thinking about how one option for R3C1 to connect up would force a lot of things and after a while it clicked to me that the other version doesn't work, which was very delightful to see

[@RobotProctor]

I think this is the hardest sudoku I've ever solved myself :). Really interesting ruleset. Thank you Jesper!

[@null6955]

if my brain and simons merged we could've shaved off a few minutes from the total bc i was screaming about the 4 arrow in the yellow region for ages. but to have gotten to the point where i could point out the obvious i'd still need simon's brain

[@zirco77]

So enjoyable to solve, and simply brilliant! I mean, to create this puzzle, not only you have to set arrows up in a minimal way to disambiguate regions (almost all of them), but the irregular sudoku it then creates must also be solvable with the very few available digits available at that point. This is mad.

[@KingOfShadeEmpire]

This was a joy to solve. Such a good puzzle! I was stuck in the orange cage for a long time.

[@jaredwonnacott9732]

I don't know why I actually tried solving this one, but, I was shocked at how manageable it was after a while. I also was pleased to go back and see how different our solving approaches were, and how we reached a lot of our conclusions in different orders and through different means, but still eventually got to the same conclusion. What a neat puzzle. Now, I think two and a half hours is procrastinating enough, I should probably go do something productive.

[@Jablicek]

Good fun and a very satisfying solve path!

[@Urutsini]

Loving watching this channel. You are amazing Simon. I'm surprised you don't use more of the program tools to help you solves. Might it have been easier to use the circle tool to mark region number cells and colour flashes when cells could be multiple options of colours?

[@fakjbf3129]

One small deduction to prove that yellow and orange must be consecutive is that if yellow was a five and pointing to a new color that color would have to be six and that would leave orange with no valid digit. So either the yellow five points to orange or yellow is a four and still points to orange.

[@MrWoorldWide]

that is one of the coolest rulesets on the channel so far, very enjoable video :)

[@Hybban]

I found the sudoku part at the end more complex than the region colouring. I found the 345 numbers in region 5 a lot faster. The ordering of region 123 was pretty simple to me just by looking at the arrows. But your ability to see naked singles always amazes me! It seems that watching you repeatedly solve sudokus help me improve a lot. Thanks a lot, Simon.

[@bertbergers9171]

At 52 minutes in, yellow has to point at orange: 1) it is 4 and points at orange directly, 2) it is 5, making orange not able to be anything but region 6 and thus yellow has to point at it. r3c2 has therefore also to point at orange, can't be 2 or 3, if 4 it points at r7c6 and orange is 5 (pointing at r6c6), this is possible (orange has 2 extra cells). If r3c2 is 5 (or 6) it points at r8c7 (or beyond) which is too far away from orange, so r3c2 is 4, r1c1 is 5 and all the known regions get numbered, orange gets defined, and we get on with the puzzle. This was available a bit earlier, but this is when Simon asks how to get on. I liked the puzzle, should have given it a go. Simon did allright, but he missed a few times (above, and when he made a 1,6 pair in blue row 5 pointing at a lot of orange and therefore putting the 1 in orange in column 6). I had to laugh when Simon said ineptitude to do sudoku :P Thanks for the video! And thank you to Jesper for the puzzle.

[@Harry-qq2ww]

What a brilliant puzzle!

[@titusadduxas]

Took me over two hours and that was after I kept restarting despite spotting the break in very early! I just couldn’t get past R4C1 not being the top left in its region. As soon as Simon got to that point and effectively showed me the error of my ways I managed to complete it and really enjoyed doing so. I really do like the build your own region types. Excellent puzzle.

[@naphackDT]

90 minutes. Love this kind of puzzle.

[@srwapo]

67:23, never really tried one of these before, so I hovered over the timeline to make sure I wasn't going down the wrong path when coloring my regions and I needed a little bit of help to see how to get the "7" cage out of there (I deduced I could go left by putting a 1 in r3c2 before I looked at r8c2 and realized it had to be a 1 right away. I then forgot to go back and see that r3c2 couldn't be a 1 anymore).

[@Lutterot]

What an enjoyable puzzle!

[@SpencerTwiddy]

A very elegant puzzle! I suspect there are only a very small number of possible settings with this ruleset that lead to logical solves

[@RichSmith77]

Terrific puzzle. I'd echo Simon's comments - I have no clue how someone can create a puzzle like this from the ruleset, with such seemingly little information provided in the grid, yet somehow it completely defines nine irregular regions, and solves to place 81 digits into an empty grid. And solves so beautifully! I managed to solve it in 79 minutes. One step I found that Simon didn't need was, at around 27:00. r1c1 couldn't be green, since it would have to point at the purple region 3 cells away, but that would repeat 3 in green. That helped me find the extra region in the top left that forced so much early on.

[@kevinmartin7760]

Somewhere after 1:01:00 Simon seems to switch from not being sure the red cells are all in the same region to being sure that they are. Also, his assertion at 1:02:45 that the 1 is not the identifying number of the red region really needs more explanation: If the 1 in R8C2 were the identifying cell of red, red could only use columns 2, 3, 4 in row 8, and then would need columns 1-6 in row 9 to make up its count. This would leave 6 more cells in the lower left that would have to be part of grey, making it too large.

[@RichSmith77]

While I think you're right, I don't believe he uses either of these in the subsequent logic. The deduction that the light green cell r4c7 is the determining cell of the 1 region is still valid (from 1:03:20 to 1:05:55). And once that is identified as the 1 region, then the red 1 in r8c2 can no longer be. (Simon explains this at 1:07:52, too.) The only time, I feel, he comes close to saying all three red cells are in one region, is when he highlights all three together at 1:02:56 and says they "must be the second or third region, I think". But he doesn't make any deductions based off of thinking they're the same region. (At 1:01:25, he explicitly states that he doesn't know if the red cells are all the same or not. Again at 1:06:35 he acknowledges that all the red cells don't have to be the same region. Then at 1:07:20 he un-colours two of those red cells anyway.) For the red 1 not being the identifying digit of its region, he's probably referring back to his claim all the way back at the start (9:48) that the 1 in r8c2 couldn't be the top left of its region. Unfortunately, this was incorrectly "proven" at the time. The second region the 1 pointed at (r9c3) didn't have to exist in the 16 cells he highlighted. It could easily have escaped to the left, and gone up column 1.

[@yto6095]

wonderful puzzle! i got a little stuck, not realizing that the upwards arrow in region 3 might be a 7. i looked everywhere for mistakes and after an hour i noticed it was so simple. other than that, everything went smoothly. it was nice to see that you got all of the conclusions about regions in the same order as me. that says quite a lot about the difficulty of the puzzle (easier puzzles have more ways of solving them and it would be very unlikely to get everything in the same order), and i'm happy i was able to solve it.

[@asbjrnfossmo1589]

This really is a gift to the universe. Very proud of getting it in sub 2hr.

[@CarlintVeld]

Would be cool if Simon could bring the setters to the channel for some background interview on how the particular puzzles came to be 😅

[@cathybryant5119]

"If I keep both these colours I'm likely to think they are either different or the same". As opposed to? 🤔😂

[@saltatio1545]

It took me 3 hours on the nose, but I managed to complete it. Thanks for the inspiration to try it, it really was worth it! After I had figured out nearly all the shapes after a little more than an hour, the realization how difficult filling in the actual digits would be hit me ^^

[@HunterJE]

43:52 Can eliminate 7-8-9 because of the arrows in fuchsia - 9 cage cannot have any arrows because they would have to point to the "10" cage

[@tiagomarques9822]

I take some pride in being brainy, but there is something that prevents me from being a fast sudoku solver: the ability of spotting at a glance which digit or digits are missing from a region, row or column. Even in normal sudoku, if I have all but one cell solved, I still need to look for all the digits in ascending order in the cell’s box (or row or column), and even if I find out that the 5 is missing I still need to check that numbers 6 to 9 are there. So I do marvel at Simon’s and Mark’s (and even my wife’s) ability of spotting the missing digits so quickly.

[@midori58]

My first 5 star difficulty puzzle solve! Though it took me 200 minutes, IT WAS STILL WORTH IT

[@yichen6313]

Amazing puzzle! The ruleset looks crazy but once you get a hang of it (things that if a color A points to another color B, there can not be a color C that points also to color B, etc etc), it's very cute. The video time sounds daunting but it's not too bad, got it in about 1 hour in the end.

[@kevinmartin7760]

Around 16:00, another completely different way to refute the 1 in R3C3 is to consider that R3C2 is also pink and must also point to blue, and since it can't contain a 1 this puts a blue cell in row 5 or lower, making it impossible to complete blue in just 9 cells.

[@xevron]

Wow... that was quite a puzzle. I found it fascinating, because it was certainly a hard puzzle (took me 92 minutes), but for the most part it didn't actually feel hard. Getting my head around the ruleset took a little while, but once I started thinking of it in terms of all cells in region N with an arrow point to region N+1, it clicked. And once it clicked, no individual piece of logic was all that hard... there were just a LOT of pieces of logic needed, and they were pretty hard to spot.

[@isavedtheuniverse]

50:20 "everything there works" considering whether yellow could be region 4 pointing to orange as region 5. Oh but it doesn't and its for such a beautiful elegant reason, I hope you find it.

[@d2bm0music78]

At 56:00 i was on the cell since it was revealed haha i was wondering why you were ignoring it !! Nice resolution thank you

[@BleachWizz]

1:09:30, ok I'm just marking my guess, but 2 regions need to go out of that, because there needs to be 3 regions inside of the 20 cells, 2 regions sum to 18 and yellow is 3 deep into the region, so that lefts 17 cells for 2 regions if yellow escaped directly out which is not enough for the 2 regions assumed to live in there. so 2 regions needs to escape.

[@TheClawNinja]

This is next level stuff.

[@oneeyedman4431]

Love the long solves, thanks Simon

[@jimmyh2137]

9:55 well actually yes it's possible. R8C2 can be the top-left most cell in the region if the region takes 7 cells in row 8 (all except C1 and C9), + R9C1 and R9C2 Then R9C3 is a different region and can escape up in C9

[@gatlygat]

This puzzle is the absolute bomb!

[@gatlygat]

I gave it a go, around 70 mins. Simon promised (guaranteed even!) satisfaction. Well, at the end I was beaming. Contentment, pride, relief, satisfaction yes and the incredulity of doing it. Thank you for your urging Simon - this was an interactive exquisite insight into great parts of human ingenuity. Stoked.

[@1manApocalypse_CP]

While watching along I actually figured out how the 1, 2 and 3 regions were formed before Simon.

[@wasp89898989]

Just solved it. Amazing puzzle!

[@liiiinder]

So how did you find the puzzle before the video was posted? Because I find it impossible that you solved it within a minute 🤷‍♂️

[@RichSmith77]

@@liiiinder It's possible they mean they just solved it in the last day or two because they just found it on Logic Masters Germany recently (or wherever else it got posted). It's not a CtC exclusive puzzle.

[@liiiinder]

@@RichSmith77 Yeah for sure, thats why I asked where he found it 🤷‍♂️

[@RichSmith77]

@@liiiinder May be it's just the way I read it, but it sounded like you were casting doubt on Akiku's claim to have solved it. (You didn't ask "where", you asked "how")

[@77kaczka77]

I agree with 5/5 and 100/100 notes. For Simon 500/500 as product

[@Coyotek4]

1:08:02 ... fully agree with Simon's assessment; know that I added this to my personal collection of favorite solves Just ... astounding ...

[@UnGeekCommeUnAutre]

funny enough, that was the most frustrating moment of this video for me. @CrackingtheCryptic as soon as you actually had your "red" 1, you could immediately deduct that the square down right was another region +1. Since the "red" 1 cannot, by any means, be in the left end corner of the red region (simple logic regarding the current placement of the grey 9 region), you could have deducted in literally 10 sec that the "red" region is region 2 and the one below is region 3. since the square from region 3 is too far from the isolated square on row 7, it confirmed that it was indeed a 3rd region, hence region 1. Instead, you spent over 8 min to come up to this by a completely reversed logic, for the sole reason that you did not pay attention to this "red" 1 square that you had marked since the very beginning of the video. I was very frustrated by this, because your brain is so brilliant that it actually allow you to solve a puzzle only 60 people on this planet managed to solve by themselves (and I would be well incapable of this feat) ... the world works in mysterious ways ^^

[@anonymoususer9837]

An hour plus well spent solving it myself, I'm still amazed I was able to work everything out! (Even if my first attempt went wrong and even my successful second try had some pitfalls)

[@StepperBox]

"No spoilers if I solved it or not" That would be a great April fools video. Uploading a video for a puzzle you couldn't solve.

[@jaydyer3999]

Fascinating ruleset and a really cool puzzle. I managed to accidentally swap the region numbers 2 and 3 near the end, but it somehow still solved uniquely after that so I only discovered it was wrong when I put the solution code in on logic-masters.

[@jongarrett2388]

Brilliant puzzle. 1hr 48 for me. Now, do I watch Simon's video as well??? Maybe tomorrow. I just kept smiling and saying "this is insane" as one piece of logic led to the next.