A New Twist On Fog Sudoku For Boxing Day

[@ryanoftinellb]

The perfect example of how a FoW puzzle can act as a tutorial for a new ruleset. Very nice!

[@Nurator]

Nurator here: Thank you so much for the feature :) That ruleset is really cool to set puzzles with. I used this to teach myself as much as the solver what hitpoint arrows imply :D But people seem to like it, so I will be back with a harder version that studies more interesting behavior of them :)

[@aendukramer]

I like it very much. But the rule description is really hard to comprehend, i needed this video to understand them!

[@rydervanwaveren]

Thanks for the puzzle! One of my favorite solves for fog

[@dralthoff1]

@ the 39 minutes, SImon says "don't forget the negative constraint". Two minutes later Simon forgets the negative constraint on the 7 clue. These guys are so cute with their little mistakes. And by cute I literally mean adorable! It's like the CtC team jinx themselves.

[@medhurstt]

This puzzle is very linear. It was inevitable the next step was going to be as a result of the last digits placed but Simon didn't really focus on them. There was also a sudoku implication of the 3 placed at the top with the 23 pair he'd identified.

[@medhurstt]

Haha..I see he saw the sudoku 3 and 23 implication moments after I made that comment :-)

[@Samhain_III]

A few minutes later he counts the cells and comments on the negative constraint for the first cell in the row,without noticing the 5 until a bit later. This is why I love watching CtC 😅

[@ryboits75]

Mark has started putting kings chess pieces on his table to remind him of the rules

[@alanclarke4646]

​@@medhurstt He ALWAYS spots the whatever about 10 seconds after I comment that he missed it!

[@Andyw83]

I love Simon. He is the most brilliant solver but absolutely amazes me at 42:57 when he asks about the negative constraints and counts right past 5 and concludes that 8 cannot go in box 4.

[@Godishus]

He's forgetting a hidden clue. The puzzle was rated two stars, meaning he's not supposed to go into the deep think tank.. but has missed something easier along the way. :)

[@scarletmanuka6170]

Same! Literally counts "5" on the square that's pencil marked 25 and doesn't notice it.

[@martysears]

An absolute beauty, definitely one of the best dynamic fog puzzles I’ve seen so far. Excellent escalation of the ruleset and journey you’re taken on with perfect choices of fog clearance throughout

[@sigawof]

Finished in 26:05 minutes, one of the rare times I'm faster than the professionals! Nice Christmas present to myself 😁

[@asktheraccoon]

that's also one of the rare times you need to do actual Sudoku to progress and well, definitely not this channel's professionals strongest suit haha

[@mxpxorsist]

simon is always slow with fog sudokus

[@PassionPopsicle]

I usually don't mind Simon's colouring. I've gotten used to it as a charming quirk. But on this one it gets really confusing around the 50:00 mark - the only relevant colouring is the blue (and black relating to it) but there are all sorts of other colours and flashes still in the way (and he was so diligent cleaning it up for the first part of the solve)

[@angelmendez-rivera351]

This is one of my pet peeves with the channel. It does not ruin my enjoyment, and of course I will always continue to support them, but it is a rather annoying quirk that the solving can get rather sloppy when it comes to pencil marks, coloring, and the rest of the tools on the number pad, and not in the comedic kind of way, which often makes it impossible to follow the explanations of the logic. I am sure many other folks have presented this criticism to the channel before, but it seems they still have to really work on it.

[@raquelmoss7207]

I feel like you’ve been more diligent with your use of sudoku and pencil markings, and it makes things more enjoyable to watch. If you made a new years resolution to clean up your colouring more once it’s run its course, I would definitely support that.

[@angelmendez-rivera351]

Amen. This is essentially the only bit of constructive criticism I have for the channel that I wish to see addressed. If not for this problem, the videos would be perfect.

[@FatoGamuTheFool]

FIRST CtC puzzle i solved 100% on my own, thank you for all the hours of teaching you provide in here, im not the smartest cookie out here (as a 30yo) so this is a really big step for me THANK YOU

[@istvanmagi473]

That's weird. Roughly half of the puzzles are easier than this one.

[@tau2647]

​@@istvanmagi473 ive only ever tried like 4 or 5 in total but ive never solved any. would you mind pointing me to one of those easier ones? 😅😅

[@FatoGamuTheFool]

@@istvanmagi473 maybe im learning and getting better, so im really proud of myself i know is dumb lol

[@Harrizeb]

@@FatoGamuTheFoolyou’ve every right to feel the sense of satisfaction solving a puzzle creates and to be proud of yourself for solving the puzzle. Congrats on the solve

[@grantfraser5430]

Yes, congratulations. I remember the frustration when I started and the satisfaction of the first few solves. The more you persevere, the easier it gets and it's now rare that I don't solve without help. Of course, some of those solves still take me 2 or 3 days. Always room for improvement, keep on Cracking! Good luck in your journey.

[@kurtu5]

I like how he troll us by counting 5 out loud. And mouse pausing on the 25 pair multiple times. Never change.

[@Shcroft2]

@@kurtu5 Simon can finish puzzles I would never even dream of starting, he is an absolute master at this stuff... But him not seeing the five left me unreasonably frustrated. I'm going to put it down to a bit too much Christmas sherry 😅

[@wordclover]

@kurtu5 It's vintage Simon - pointing out a bit of logic to his thousands of viewers and then instantly forgetting about it himself while he goes hunting for new tid-bits to tell us. 33:05 as solver #5000

[@Ferrastar]

Simon, for your Apple Watch, you’ve likely got it to mirror notifications from your phone and have notifications on for movement (stand, move etc) so you’ll probably need to go into the watch app on your phone and turn off a lot of the notifications

[@danielcummins5092]

At 20:45 in Simon's video - those two arrows in row 7 were my favorite clues to solve...the logic was very smooth and clever.

[@A_CC_K]

Yes a fog of war puzzle. My favourite type of puzzle, made even more interesting with dynamic fog. Best way to spend an evening.

[@matthiasney4871]

Everything in this solve was so beautifully simonish. Deleting the negative constraint colors in c9 (not consequently coloring the negative constraints would cost him later a couple of times), but keeping the colors in r7 for the rest of the puzzle even though they were only useful for a ten second logical deduction...

[@sebastienlecoq3956]

Awsome ruleset. I can see the power of it way beyond sudoku. Simon early : there is a sort of negative constraint Simon later : it's not the negative constraint.... except it is.

[@adamheywood113]

Thank you Simon and Mark, and Sven of course, and all the testers and staff (you know who you are, even if I don't) and Happy Christmas to you all Easily one of the best channels on KZbin

[@angelmendez-rivera351]

I think dynamic fog of war puzzles are my favorite puzzle type for this channel, if only because this is the only puzzle type in which Simon is completely forced to exhaust all forms of sudoku and puzzle logic at a given stage of the solve and region of the grid before being able to move to the next. It in turn also forces him to have to clean up his pencil marks, which he usually never does. It does not force him to clean up his coloring, but improvement is still improvement.

[@sjm6280]

Not removing colors when they had served their purpose made for a so "dirty" grid, specially in a fog of war puzzle

[@angelmendez-rivera351]

I strongly agree.

[@ColinKenney]

This was my favorite puzzle in a long time. I absolutely love the new dynamic fog mechanic, and the hit point arrows are tricky in a very fun way. Excellent puzzle!

[@chocolateboy300]

I finished in 26:52 minutes. This was a really nice approachable fog of war sudoku. The dynamic fog was used nicely here to guide the way in what is a very cool ruleset. I dug this ruleset very much and look forward to it in the future. I think my favorite part was resolving the double arrow set in row 7. That was super fun to calculate and led to some nice deductions. As always, it feels good to beat Simon's time. Great Puzzle!

[@Dasius2]

I think this puzzle demonstrates how helpful the ability to put a red pencil mark in a cell would be. You could mark a negative constraint in red alongside some blue digits. That said, I wouldn't be surprised if that is possible already seeing how good the tool is already.

[@stevieinselby]

There are definitely times when that would be useful ... but TBH I think it's overkill _here_ - in this puzzle, by the time you're in a position to make any deductions based on the negative constraint you've got several other digits looking at the cell in question so it isn't unreasonable to just pencil-mark in the 4 or 5 options that remain as possibilities.

[@hasui7610]

Hope you had a great holiday! It's interesting how as a viewer I can sometimes see things you don't see yet. But somehow when I go solving on my own I just get fully stuck. Much respect for your sudoku skills!

[@MeriaDuck]

The poor arrowed five in box six... My dog came asking me why I was frantically whispering to my screen again.

[@PassionPopsicle]

Usually I post a timestamp for other fellow screamers for the point he fixes is - but in this one he just doesn't! Poor, poor little 5 (edit: He doesn't even acknowledge it when he fills it in!! 😂)

[@Andyw83]

Eh he solved it right at the start didn't he?

[@slamcatX2]

Yup, that poor 5, it was driving me mad. Possibly, he thought the 1 and 4 in the west direction solved it even though the arrow pointed east.

[@SVURulez]

@@slamcatX2 He solves that at 14:47 (deducing that the total had to be a 5 because the 2 was ruled out). I'm not understanding why multiple people are upset about this one??

[@SharienGaming]

wow thats a fascinating ruleset - i love how this works with the fog i think dynamic fog is the single best variant ruleset that has been made and these arrows work amazingly with it

[@strawberrymilk3695]

25:59!! So proud of myself today, it was so much fun, thanks for the puzzle

[@stevenbetts666v2]

I hope you both had a good Christmas Simon and Mark! I spent the morning doing the puzzle I suspect we will all be seeing tomorrow!

[@Tringard]

there has to be a less confusing way to write that rule

[@swaltner1234]

Apple Watch - Use Theater Mode To activate theater mode on the watch, press the button (not the Digital Crown) to bring up Control Center, activate the button with the comedy and tragedy masks (two faces). In this mode, all notifications are silenced and raise to wake is disabled to avoid interruptions in a dark room. You can still activate the watch by touching the screen.

[@benjaminrealy5661]

28:46. New favourite style of puzzle. Lots of maths and counter-maths. Kept my brain busy. 10/10

[@gi0nbecell]

Simon‘s uncanny ability to immediately ignore any logic he‘s used once and his stubborn refusal to re-use that same logic even if it‘s screaming in his face (and he even hovers over it) never ceases to amaze me - not least because he‘s still so much better at solving any logic puzzle than I will likely ever become. But come on… around 44:30 he thinks about the negative constraint, counts the cells from the 7 clue in r6 and concludes (correctly, I might add) that r7c1 couldn‘t be 8 as it would break the 7 _and then refuses to realise that _*_this exact logic_*_ has removed 5 from r7c4 ages ago._ What?

[@PassionPopsicle]

He even highlights the five while counting

[@confusedSoulof2010]

Saw this on Artisanal Sudoku, I believe, and my brain couldn't wrap around the ruleset. Now I understand and solved it in 36:03!

[@stevenrburgoyne]

Great video! Tip with the Apple watch, don't force it into your life. Let it slowly help with things otherwise you will hate it/find it useless. Start by having it be time and notifications only, then maybe if you are in the kitchen ask it to set a timer, or find a recipe. If you are out on a walk, after 10 minutes it will "ping" you to ask to record the walk. This data will get logged automatically. Try wearing it to sleep to track your sleep patterns. More and more it will assist with certain tasks but don't force it.

[@MonkehBuns]

This was a really fun one! I managed to brute force my way through it and then enjoyed watching Simon using more elegant logic to solve it. 😅

[@user-kn8bu8ue6z]

I am absolutely ecstatic rn Whenever I try these puzzles, i usually take twice as long as Simon But after taking a long hiatus from sudoku I was able to solve this in ~57 mins! This might not seem like much for most people But I used to think for the longest time that I'll stay mediocre at sudokus

[@praematura]

I stumbled several times through this puzzle, but somehow managed to finish in 29:20 (conflict checker off), so I think I didn't do too bad! 😅 Definitely some obvious deductions I missed, but happy with the solve overall. Many thanks to Nurator for a wonderful puzzle!

[@avishjha4030]

At 29:59, why can it not be 7 or 8? Since we know that green has to have 2, 8 not being possible makes sense as it would take the total to 10, but why 7 is not possible?

[@levipickett497]

7 is already constrained to row 7 in the 678 triple "by sudoku"

[@sakka350]

Because 7 is in row 7 by the 678 triple.

[@Cryobot]

Because there's a 678 triple in R7 C7-9

[@Vorash00]

Dynamic fog forcing Simon to do sudoku in sudoku puzzles what an awful innovation to come to the world of variant sudoku. 😂 making us go back to basics! lol

[@OlegHikaro]

First time I've tried solving one of these puzzles. Finished in 94 minutes, but Im proud of myself. That's a good mid level puzzle, good luck everyone

[@piarittersporn]

Great puzzle. It took me a while to understand the rule completely but after watching Simon a few minutes I've got it.

[@kikania]

I think this is the first time I was able to solve a puzzle faster than Simon (37:37)! Of course, he takes a long time to explain every of his steps in detail, but I am still proud :)

[@adrianhead6272]

I love when Simon takes a hour to do a puzzle I do in 14m20s. It's LOGIC!

[@penningmeestercgkdelft9159]

It's so much fun to behold that the un-generous fog clearance at the start of the puzzle is just forcing Simon to do sudoku 😀

[@vjay4297]

Simon, I admire your genius yet have to remind you that these are NOT colouring exercises. You can remove colouring once it served its purpose. And please do... 🙏

[@kerogandhe3846]

ty for giving us this puzzle, it rly boosts my confidence solving this and I desperately need that

[@e.m.b.5090]

Another lovely "pause video->think for 15 minutes->let video run for 3 minutes so Simon can catch up and give you a hint->rinse and repeat" type of sudoku

[@andymoss]

24:09 Why on earth did Simon reapply the coloring here?! Edit to add: Loved the puzzle, hated the coloring. Please , please, please, please remove once it has served its purpose. Please.

[@Ferrastar]

I was wondering the same, also noticed that when he ‘tidied up’ the pencil mark in row 2 he took out the 4 that was flashed as green. He might have noticed that it was no longer contributing if left in

[@JohnDBlue]

I thought I'd find a comment about that coloring but surprised it's not what I was thinking about... Now it irks me doubly 😅 See my issue was the fact that Simon was referring to the dark pink as purple and the purple as blue

[@cenzuram5301]

its first time, when i solve a puzzle faster then Simon) Hi from Poland/Belarus)

[@rK4n3]

I liked this puzzle a lot! But I got really confused at the beginning as the Android app doesn't handle dynamic fog correctly; it showed the 4-way arrow in r4c6 as its first reveal. I had to watch the video to realize I needed to play in the browser. Hopefully the app can get fixed at some point because i really enjoy the dynamic fog puzzles.

[@sheridanvespo1269]

@@rK4n3 I had the same problem!

[@mister-8658]

My recommendation with most Apple products is to submerge them in acetone for at least 6 hours.

[@brianj959]

😂

[@katiekawaii]

I loved that puzzle. Thanks, Nurator!

[@13vatra]

R6C4, the bane of Simon's existence. Even when verifying it's not the negative constraint he still somehow glossed over it 😅

[@thejuggler42]

Really lovely puzzle, well done Nurator :)

[@wanderlustwarrior]

39:06 for me. I had to restart a couple minutes in once I understood the rules better, but that was quite fun! I am enjoying these puzzles where the fog clearing isn't predictable. It's a challenging anxiety.

[@roccov3614]

A very satisfying puzzle. I loved the sequential nature of it.

[@mikes_.5_cent]

Thank you, and Merry Christmas Simon.

[@brianarsuaga5008]

Quite cute puzzle, this arrow rule was very tricky for me, but once I got the hang of it it wasn't so bad!

[@victorcarrasco4248]

Oh Simon should set a ‘solve’ focus mode on his phone. That would solve the problem he mentioned during the rules section

[@HunterJE]

22:21 Once it's identified that all four of those cells must contribute to one or the other arrow you can also immediately center pencil mark each cell down to two options, since each cell must be filled with its position vis a vis one arrow or the other...

[@1985elfy]

You can go further than that: there must be an inner sum and an outer sum. For each square the two pencil marks are n (pink) and n+1 (purple). Any pink cell rules out the possibility for the cell to its right to be purple, because they would be the same number. So it resolves entirely on its own without needing to refer to the 3 further up the grid.

[@shawnmichajluk2044]

Fantastic puzzle and rule! Important to remember that a correct number clears the fog from the cell (and possibly others). I kept going, then realized I made a mistake, and then realized that fog did not clear from the cells where I put in a number.

[@kristerlarsson4633]

This is the best puzzle in a long time. Challenging but not overly so.

[@johnathandoe6034]

We need to make a dynamic fog of war, where the top left square reveals the entire fog if you get it correct to troll the guess and checkers!

[@diddlmus]

Its a Nice puzzle. Solved this Yesterday - I Think first time I have solved a puzzle, before its on this Channel

[@davidhughes7174]

What a puzzle, beautiful. Thank you Simon.

[@dennisb8332]

This one was "easy" compared to the others you usually solve, thank you for that! :) Took med 19min and 7 sec

[@Armoterra]

25:11 the one time we don’t want Simon doing sudoku, he goes and does sudoku.

[@chaseedwards7024]

I love the fog of war puzzles. Took me a little while to fully understand everything those arrows were telling me - that was a really fun puzzle. 54:54

[@sorrowinthewind4258]

Just under 30 minutes. One of those rare cases where I'm faster than Simon lol

[@inf0phreak]

I think what broke my brain when trying to understand this at first is that the arrows (at least to me) seem like they're the wrong way around. As I followed Simon's solution it suddenly became clear to me that I understood the logic *much* better if I mentally flipped the arrows and asked questions like "there are two arrows pointing IN to the lower right cell in box 3. Could it be that only one cell lines up and is added to the total of this cell?"

[@xerodeus2337]

00:31:55 solve time! This was a relatively fast one for me by my standards! Once I figured out how to visualize the way the arrows worked it started unfolding pretty quickly! Lovely puzzle!

[@mattconco]

"It's not the negative constraint is it?" Yes yes it is Simon... 😂

[@MisterM2402]

Solved in 20:56. Rules sound a bit confusing. I'm sure Mark did a puzzle with the hit-points rule recently and that was written more clearly. "[...] while every other digit in that cell would not" makes me think of a single cell with multiple digits in it but I'm guessing it just means if the 2 were replaced by a different digit.

[@williammorris7279]

Yes, I would have preferred it to read "..... while any other digit in that cell would not." It didn't help me that the words Simon used when reading out the rules do not match the written words.

[@ChicanoryIsMyName]

I did fine after watching the rules. I'm glad he gave a good explanation.

[@geoff544]

Same. Wouldn't it be better to say '.. ANY other digit in that cell would not.' rather than 'every' other digit, since there can only be one digit in a cell?

[@gregind01]

Simon's song is quickly becoming No christmas 3 No christmas 3 Where for (4) art thou corners?

[@RianneOK]

Finished in 73:23! Loved this one. Only got stuck at one point and just started doing sudoku until I found the little thing that I missed that there was now only 1 place the 1 could go in box 5 and then I was rolling again because of all the pencilmarking I had done in the meantime. Super great. :D

[@thescrewfly]

Is it just me or is the "blue" Simon uses actually purple, while his "purple" is more like a pinkish violet ? Do I need to get my eyes tested?

[@adonnapryor5440]

Merry Christmas and Happy Boxing Day! This was a fun puzzle!

[@Xiuhtec]

31:19 solve for me, which I'm pretty proud of given my usual plodding. Fog is always great for knowing where to look next. Took me a few minutes to get the hang of how the arrow logic really worked but flowed very well once I did. Love the dynamic fog and what it allows to be done! (In this case the puzzle would work just as well without fog at all, but being shown exactly where to look when is so much nicer than having to guess or intuit.)

[@peterhaagen8506]

I had to watch half the puzzle to understand the rules😵‍💫. Not native speaking English. 😊. Now I know the rules and it’s fun. ❤

[@aliengeo]

Texas doesn't have a ton of mince pies, though I've had mincemeat before, but a family member has English expat neighbors so I did actually get to try some this year!

[@ferociousbiscuit]

Columns 1, 5, and 9 have an interesting semi-swordfish logic to them. Each column requires a minimum of 2 cells to add to a distinct digit but are unable to share any contributing digits. With a minimum of 6 digits adding to a maximum total of 24 (7, 8, 9) you must use the digits 1, 2, and 3 as contributors. This creates a swordfish on those digits in rows 2, 3, and 4. 2, 3, 4, 5, 6, 7 adds to 27. 1, 3, 4, 5, 6, 7 adds to 26. 1, 2, 4, 5, 6, 7 adds to 25. 1, 2, 3, 5, 6, 7 adds to 24. (First viable sequence). This logic isnt really necessary or faster than what was used in the solve here but I found it interesting.

[@markp7262]

25:07 finish. A very nice ruleset, with some cool tricks you can use to solve. Excellent!

[@Foxyjosh]

Best games of 2024? If Sudoku isn't on the list, the list is wrogn.

[@jimbothefuzzy]

Seeing Simon get a news alert for the "20 Best Games of 2024" makes me think there needs to be a list of "25 Best Puzzles to Do in 2025." Which would be taken from some of the best puzzles that REALLY deserve more attention. Though I'd personally argue the Rat Run puzzles from Marty Sears deserve a spot on the list (though I'd just put the entire series as one entry, so as not to clutter the list), even though they're already very popular. Also, only giving it one slot means it automatically includes any additional puzzles Marty might add to that series in the future. I'm far from qualified to write that list. I don't have the time to solve enough puzzles. So I'll leave it to those who do have time. And I'll make sure to try at least some of them.

[@GuardOfGaia]

One of the very few times I've beaten Simon's time albeit only by 3 minutes but as the negative constraint looked to be extremely important in this I limited colouring to marking off completed arrows.

[@jimlan2599]

Absolutely loved this puzzle!

[@NewbStory]

I'm not sure if this has happened to anyone else, but I was immediately stuck as I thought arrows were meant to be solved separately. So the very first cell shown (r3c7) was unsolvable. Glad Simon quickly showed it wasn't the case.

[@Harry-xu9vc]

what's the difference between corner pencil marks and central ones?

[@brianj959]

Well, they can be used however helps you to solve; but Simon uses them as: - corner pencil marks indicate where in that box a digit could go - central pencil marks indicate the complete set of possible digits remaining for that cell

[@Entapris]

Great puzzle. Really enjoyed that one! 32 mins

[@dominicsymes9189]

Simon counting right past 5 in row 6 when thinking about the negative constraint 😅

[@srwapo]

23:55, these arrow sudokus usually cause me trouble, but this one just flowed. Good thing I remembered that for the three clues pointing down in row 1, they could only see one cell in each row total (one 1 in row 2, one 2 and row 3, etc).

[@nilshubinette4932]

This is a lovely puzzle!

[@kongking4868]

46:39 took you long enough lol i actually fond myself talking to the screen, "its right there"

[@asix6]

How do i fix that: On my Android App the fog clears around the correct digit. not as intended.

[@dumasyann]

Same here

[@piasecznik]

After a brief false start because I assumed every arrow had to have a valid cell on it and then watching the rules section of the video, pretty easy going. 34:56, but I didn't restart the time, so probably closer to 25 minutes after I understood the rules.

[@jimlan2599]

I made the same mistake at the beginning ...

[@romainbricout1713]

I think it is the first ever featured sudoku I managed to solve! 39 minutes for me 😊

[@whypick1_]

Solved in 23:21, but needed almost that long just to understand what the hell the the arrow rule meant. A possibly better description: For all cells that have an arrow in them, that cell's value is equal to the sum of all cells in the indicated direction(s) whose value N is also equal to the distance to the arrow cell.

[@werefrogofassyria6609]

love that rule set, took a bit to get used to it, though.

[@thefallenarm589]

Interesting rule ; puzzle ended quite simpler than what it looked at first.

[@PoignantPirate]

53:35 Can someone explain why r6c9 is forced to be included in the total for r6c4? r6c5 + r7c4 + r8c4 is a total of 6... I just can't see where the assertion came from.

[@cozyvrc]

around 44:57 I was just as stuck as Simon but then I noticed that the fifth spot away from yellow couldn’t be 5 due to the negative constraint, I checked because of something he said funnily enough So for the first time I was just as stuck as Simon but figured it out before him Other times when I spot things before him it’s because I notice them as soon as they’re available but he gets distracted with other things and forgets to check I feel proud of myself for this one because I actually worked this one out while he was trying to