The Newest Form Of Chess

[@gdc42]

Thanks so much for that feature! This puzzle was inspired by puzzles from zegres and jeremy dover who introduced the "keypad knight line". I still remember the day when I first encountered those and thought "what crazy minds would come up with this?". Excellent work on the break-in from Simon (as expected)!

[@zegres]

Love what you did with this!

[@puritan7473]

Brilliant puzzle, thank you gdc!

[@skywavelincoln]

Brilliant puzzle! Simon says you took it to the max. I think you can do better. Knight Snake (snake line where digits have to move along knight moves on the numpad)

[@olivier2553]

That is a very elegant and fluid puzzle.

[@Paolo_De_Leva]

Stratospherically beautiful construction 👏👏👏👏👏👏👏👏👏👏

[@Ardalambdion]

A former chess grand master started to work at a restaurant and the guests shouted Cheque Mate all the time.

[@Hertog_von_Berkshire]

If we were in the US, it would be "check" but almost certainly not "mate". If we were in the UK, it would be "bill" not "check". Maybe the joke would work in Australia or New Zealand. There, I acknowledged that it's a joke. Be grateful. 😄

[@jonlittle5032]

@@Hertog_von_Berkshire Americans aren't rubes, mate. We get it. Just took me awhile to get off the floor.

[@falloutfan2502]

Works around the world, if you do it with an Aussie accent! :)

[@iaincook5835]

Before that, they'd point at the bread and say "Stale, Mate!"

[@jdyerjdyer]

I asked for a good fork and wasn't disappointed!

[@neilkightley3451]

GDC has finally made Simon use the number pad!

[@HunterJE]

He's "used" it in a similar reference-only way for the rule of thumb on mod-3 groups...

[@Esperi74]

@18:52 you can rule out odd digits on the bishop's line very easily because all the odd digits in column 2 have been placed.

[@Waggles1123]

You can also rule the zig-zag bishop as being all odds without solving the long knight, which is how I started. If you start at either end with a 2, the middle space must be an 8, and then the 5th space has no valid value (since it sees 2 or 8 and would need to be 2 or 8). Since this holds for any starting value (since hopping between even digits is cyclical and symmetric), it must be odd, which makes the horizontal bishop even, and the rook is then all odd and can't contain a 5, which gets you the 5 in r2c1, and then in r5c2. It doesn't necessarily help to go this route before the long knight, but it does make the zig-zag bishop solve a lot faster than trying to work through it in one direction based on the digits left over from the long knight.

[@TheBioRules]

I actually started with that Bishop line, because its 4 digits that all see each other. If a Bishop is on the diagonals, the most digits it can do is 3 before having to revisit a 5 in order to shift to the other diagonal, therefore it must only use evens. Then because the Rook line next to it is also 4 long without a repeat and can't use evens, it must use the corner digits. So 5 is set at the front of the row off the bat.

[@Qurqirish_Dragon]

@@TheBioRules But a bishop doesn't have to go 1 space at time (as a pawn or king does), so it could, for example, go 7-3-5-1-9, allowing all 5 odds to be on the line, even if they all see each-other. (If I am reading your comment correctly)

[@5t757]

24:19 for me. All those hours spent as a kid trying to mentally hop between the brown tiles on the bathroom floor using only knight's moves have finally slightly come in handy.

[@inspiringsand123]

Rules: 02:13 Let's Get Cracking: 06:56 What about this video's Top Tier Simarkisms?! Bobbins: 2x (31:50, 35:05) Phistomefel: 1x (03:18) And how about this video's Simarkisms?! Ah: 9x (06:00, 11:08, 11:08, 11:29, 28:54, 31:29, 35:02, 37:47, 40:04) By Sudoku: 6x (13:52, 30:29, 32:06, 34:22, 34:33, 35:19) Clever: 5x (01:23, 12:03, 12:06, 40:40, 41:04) Lovely: 5x (00:39, 06:34, 14:35, 22:46, 39:34) Gorgeous: 4x (17:53, 39:39, 41:37, 41:39) Obviously: 4x (06:08, 06:23, 07:41, 15:50) Good Grief: 3x (24:00, 29:26, 40:36) Sorry: 3x (08:17, 08:17, 22:29) Beautiful: 3x (36:04, 41:02, 41:18) The Answer is: 2x (29:10, 40:44) Bizarre: 2x (01:59, 17:15) Unbelievable: 2x (03:09, 03:12) In Fact: 2x (19:26, 40:16) What Does This Mean?: 2x (26:32, 27:22) Pencil Mark/mark: 2x (31:12, 33:54) Weird: 2x (21:37, 37:27) Naked Single: 1x (31:36) I Have no Clue: 1x (26:34) Brilliant: 1x (30:47) Incredible: 1x (03:00) Ridiculous: 1x (17:49) Take a Bow: 1x (41:48) Hang On: 1x (21:08) I've Got It!: 1x (39:14) We Can Do Better Than That: 1x (19:55) Most popular number(>9), digit and colour this video: Forty Eight (3 mentions) Three (68 mentions) Black, Green (2 mentions) Antithesis Battles: Even (15) - Odd (11) Outside (2) - Inside (0) Black (2) - White (1) Row (6) - Column (6) 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!

[@sofussverressnnfinne204]

I enjoy clicking through all the time stamps just hearing "ah, ah, lovely, lovely, lovely"

[@HunterJE]

18:52 "If this is odd numbers..." Could skip a few steps here, as already noted c2 has its complement of odd numbers, so r2c2 must be even and by extension so must its bishop line...

[@stephenbeck7222]

Right I was confused what Simon was going on about with hypotheticals. He had already established that R2C2 was even.

[@patrickgass787]

Such a treat to see gdc featured! Their puzzles are always interesting, always innovative and always the best possible expression of the logic.

[@n8style]

Got a little lucky at 22:10 with R2C8 hehe

[@46lespaul]

I thought i was crazy glad i wasnt the only one who noticed

[@ilsekleibscheidel7219]

@@46lespaul you were not. I didn't trust myself and turned the video back, because this is not the kind of error Simon tends to. He usually only hits the wrong number, while saying the right one. But luckily this didn't affect the solution.

[@iaincook5835]

Introducing Harry Styles into a chess-themed Sudoko with a "one direction" pun was genius.

[@colej.banning2419]

I didn't get the pun until you explained it just now, so thank you.

[@blobz-1]

“You… Shall Not… PASS!”

[@davidrattner9]

Can't wait for your LOTR hunt!!

[@anthonydomoracki4850]

What a fabulous puzzle and solve. Only thing it needed was a pause the video moment. Lol

[@mstmar]

The whole video i was wondering if simon would ever realize he has a number pad on his screen (on the app). turns out, no he does not. granted it might be inverted, but it still has the same layout and so the same restrictions

[@srwapo]

I actually spent some time looking at the number pad on my keyboard and the number pad on the mobile app and wondering if it mattered that the order of the rows was flipped (it doesn't).

[@droid-droidsson]

there's an option in the app to flip the digital number pad (to the layout of a keyboard numpad).

[@mstmar]

@@droid-droidsson You can flip it but like i said, it still has the same restrictions as the uninverted version. also me being used to the univverted version, i would be missclicing a lot.

[@mikewyka5733]

I thoroughly hope to see more puzzles with this rule set. Approachable enough to wrap my head around the rules, but challenging enough to feel quite rewarding when making progress. What a wonderful puzzle. Hats off to gdc! Cheers (Or perhaps I should say check)!

[@martysears]

That finale with the queen was absolutely perfect, one of the nicest endings to a puzzle I have seen recently. Lovely work mate!

[@MasterHigure]

The chess pieces jumping around on the numpad reminds me of an old XKCD comic ("Explorers", number 839). A bishop and a knight is on a 3x3 board, and they are not getting along at all. Also, the emergent parity rules (bishops lines stay on a single parity, knights alternate parity) are quite cool.

[@titusadduxas]

57:15 - What a brilliant and original puzzle. Some great logic there. I was a bit slow at spotting the implications of the long 🐴 line but I thoroughly enjoyed every minute of it! Thanks @gdc42

[@HunterJE]

13:20 "This could be different or the same as this digit" In a vacuum, maybe, but since you already have the other 26 in that box from the other end of the sequence it's forced...

[@Sponsie1000]

Very fun concept and puzzle!, wouldnt mind doing more of these in the future :]

[@anaayoung9142]

I solve this one a while ago, and I am happy to see this rule here on the channel! 🎉

[@travisbosco8469]

Excellent puzzle and solve by Simon! I really, really enjoyed this one.

[@geezerama]

Stunning stuff, to recreate chess constraints on a numpad and apply to a sudoku grid is genius, thank you Setter and Simon.

[@redstonekid2222]

Solved in 44:26. The break-in with the giant knight line and the ending with the queen line were both hilarious.

[@boydegg]

38:04 .... I'm blown away by how clever this puzzle is. I love chess constraints and this is a beauty.

[@Gordonfreems]

The knight lines becoming a more restricted german whisper lines is so interesting

[@LiquorStoreJon]

Another fun, wild and interesting rule set!

[@Hakucho64]

Needed help with the break-in about the string of legal knight's moves, but got the rest out with no problems. Lovely interaction between sudoku and chess logic!

[@calculatrguy]

One of the most fun puzzles I have ever solved. Being a chess player definitely gave me a head start knowing that the knight always alternates colors when it moves.

[@tezza7]

Great puzzle and solve Simon! I think it would be cool if you could let us know how difficult you feel each puzzle is out of 5 stars after you've solved them? This might be a nice interesting addition to the closing of each video.

[@AFT3RDAY5]

That is a brilliant puzzle 👏🏻👏🏻👏🏻 I loved every step of solving it. This way of incorporating chess movements was so much fun. Give us more please 😄👍🏻👍🏻👍🏻❤️

[@Jalo1138]

That was so much fun! That ruleset what definitely my favorite in a long time. I focused on the puzzle as a parity puzzle for a bit too long, but it definitely helped me to make good headway at the start.

[@Qurqirish_Dragon]

Note that in the software, although the numbers are a mirror of the numpad, the number grid there is effectively identical to the numpad, so Simon didn't HAVE to look down for it.

[@Kinada]

50 min, that flowed really well considering I had no clue where I was going to start when I looked at the puzzle.

[@steeevealbright]

This took me 8 hours (with the middle 7 hours being mostly just staring at it over multiple days), but I did it. I did it without any help. And it was amazing.

[@PauxloE]

17:32 "So these are all even digits, this is going to turn into a parity puzzle" - I wondered how Simon only now noticed the parity. A bishop is staying on its parity, while a knight (and pawn) is always switching parity, this is how I started it.

[@nightwishlover8913]

Wow! How did Simon see that chain (on the long knight line) at the beginning so quickly??

[@zeam-h3133]

The pawn is restricted from being totally harry styles esque 😂 a one direction joke I didn’t see coming

[@markp7262]

20:31 finish. A fun little chess puzzle, although I don't use the number pad myself and had to keep referencing it. I color coded each side of the knight rotation from 7 to 3, making it a bit easier to see where things fit (on the knight lines, anyway). Excellent job!

[@Glamador]

I really adored this puzzle. I hopped on the parity train from the start, beginning with the zig-zag Bishop line. I determined with ABCD analogues that it could not be an "even" bishop line, which followed that the adjacent bishop couldn't be odd, which pointed to the rook line as being comprised of all odds. I enjoyed starting there because it made the unfolding of the long knight line even more satisfying as I already had a bunch of pencil marks above to be unraveled with the precocious pairs that the knight pointed to. Just great fun.

[@piarittersporn]

Splendit idea. Great puzzle, much joy.

[@FrancisFjordCupola]

Now there will probably be one setter evil enough to make a puzzle with chess lines where Simon will have to deduce to which piece each line belongs. With one line being wrogn.

[@RichSmith77]

Shouldn't Simon be able to see the layout of the numbers on his screen, by looking at Sven's input panel? There was no need to keep looking down at his number pad on his keyboard.

[@dustpan5356]

Was going to comment the same thing….

[@AaronSmith-i8y]

He might have his video recording covering that bit?

[@dustpan5356]

@@AaronSmith-i8y Possibly for this video, but for others where he uses the pen tool he would need to be able to see it, so he obviously can see the number pad sometimes at least.

[@chocolateboy300]

I finished in 71 minutes. This ruleset took me some time to figure out, but I feel like I picked up on a lot of its tricks. Bishops always have to be odd or even. Knights can't have 5s on them and cycle through 8 numbers unless able to turnaround. Knights alternate between odd and even. Pawns of three length in a row must always have the center digit be from the center row. Rooks need an even digit as a transfer junction to get to 5. I'm excited to see what others do with this ruleset, because this feels very malleable with other rulesets. Great Puzzle!

[@benwhite5734]

If you ever do a puzzle with this rule set again, you can illustrate the moves each piece can make by just clicking in any of the 3×3 boxes. For example, click on cell 8 of one of the boxes, and then you can click on cells 1 and 3 to see how a knight can move. This might be easier than looking at the number pad or even the numbers over on the side in the software and having to mentally visualize it. The top and bottom rows will be swapped, but that doesn't affect the solve.

[@Gonzalo_Garcia_]

12:47 for me. What a fantastic idea, maybe it's not for everyone, but I personally loved it. Great puzzle!!

[@seanb7807]

20:55 for me, very happy with my solve. Played a good amount of chess in my life which helped; the main thing for me was finding the long knight line break in almost immediately (realized there could only be one sequence that landed you on 7 for the 8th digit in the sequence) and the rest flowed from there. Really cool idea and a very fun puzzle!

[@harriethogarth372]

"we'd only be allowed to do pawn moves..." 😂😂😂

[@Priscellie]

Such a fun puzzle! I really enjoyed this mechanic.

[@gibbbon]

finished it in almost one straight hour, this puzzle does make you think, but, it is still accessible if you go at it step by step

[@Paolo_De_Leva]

Stratospherically beautiful construction and stratospherically masterful solve. 👏👏👏👏👏👏👏👏👏👏👏👏 Thank you *gdc* and *Simon*

[@whelmking6497]

Fun and surprisingly light for me. Took a bit of experimentation after discerning the five numbers on a line in R6, but smooth sailing after that. A rare win over Simon. 29:19.

[@compiling]

37:29. Took me a while to see what was going on with the 7 in box 2, after that it was a pretty smooth solve. You can get a lot of info out of odd/even colouring with this ruleset, since bishops keep the same parity and knights alternate parity.

[@TheRevmack]

I’m so happy! This is the first sudoku from this channel I’ve ever solved. I’m a chess master so I really wanted to try my best at a “chess” sudoku. Why does this feel so exhilarating? Lol

[@TheRevmack]

I forgot to say but it ended up taking me an hour and a half

[@RichSmith77]

Congratulations. It is a great feeling, isn't it. Not the easiest, for your first solve!

[@gdc42]

Congratulations! And don't worry about time. Simon just makes everything look so much easier than it is 🙃

[@AaronSmith-i8y]

I did use parity coloring when solving. It nearly screwed me up because the first rook line you think about is all one parity but of course this does not mean that rook lines can never have digits of both parties, just that a certain parity must always have a buffer between them on the line.

[@gumbarius]

I would say the knight line would be the most interesting to have as a "basic rule" Adding all of them would probably need too much explanation all the time and most of them don't really feel as restricting But who knows

[@fatercoelho7476]

yeah, really enjoyed it, maybe my fav sudoku yet!. quite sad i made some simple mistake and had to go back 20 digits, but it's still quite a great concept to look at the pieces in the keypad context

[@MarkWiseTechno]

47:43 for me today and without any help from the video! Quite a pleasant solve and a very unique idea!

[@psiphiorg]

Intriguing puzzle. I ran into an issue because I accidentally reversed the 6 and 8 in box 2, because I didn't double-check the number pad before filling them in. Fortunately, once I discovered that and fixed it, I was able to re-use most of the logic that I had discovered before to get back to where I had been. My time was 34:37, solver number 6228.

[@xitvono]

Simon, I recommend using the numpad when you do sudoku. Also, you can enter corner marks while holding shift, and you can enter central marks when holding control. That way you don't have to press a key multiple times to enter a digit.

[@Orenotter]

Instead of limericks, now I choose To rhyme a rhyme like Doctor Seuss. To speak Iams in rows of four And thus a new form I'll explore. Till today I have not ever Seen a puzzle quite so clever As this chess sudoku grid. I'd remember if I did. Twas a little scarity Till we saw that parity And patterns came along to guide us Bringing answers from inside us. Fingers dancing, keyboard blazing, Simon once more proved amazing, Brimming with such mental power, Coming in below an hour! Now the puzzle has been done through. We al had a lot of fun, too. While we all were donut snacking, As we did our cryptic cracking. From Fnaire and I (the Ma and Pa) Kids, grandkids and kids-in-law, Simon, you've our thanks and praise. They'll be back in seven days.

[@themuffin437]

21:05 for me, loved how the queen line came into play

[@Squishy3757]

Of course Simon’s number pad is upside down.

[@NekaSulia]

found this one pretty easy, I found it easier if you color the squares. finished it in 72:18. Could have finished it quicker, but I made it a point to finish the coloring before finishing the puzzle

[@veggiet2009]

30:42 "box 4's been filled in" Me: *waiting for Simon to notice which box 5's must be in on line 6 for about 25 minutes now*

[@AngelWedge]

As soon as I saw these rules, a related ruleset popped into my head for which I can already see some interesting bits of logic even without a concrete puzzle in front of me… but I suspect I don't have the spoons to build a human-solvable puzzle on it.

[@aahaanchawla5393]

Got it in 73:02. Ive been watching since a few years but never tried a puzzle. This was the second one that I was able to solve

[@danma84]

One major thing I struggled with: How can a bishop jump from 7 to 3? Isn't the only way out back to 5 again? Should I just assume the numpad repeats at the edges?

[@MattYDdraig]

28:10 This was brilliant once I'd remembered the orientation of a number keypad 😂

[@annikaQED]

Loved this! I felt like I was down the rabbit-hole in Wonderland, playing a weird sudoku with Alice, the Mad Hatter, the White Rabbit, etc. It was great how the stalwart pawn plodded his way straight ahead, from 2 - 5 - 8, breaking open the rest of the puzzle. There is so much room for exploring & developing this rule set. I'm looking forward to this rule set in a FOGGY landscape. Lewis Carroll (Prof.Dodgson) would approve. Beware the Jabberwock, my son!!!

[@gdc42]

thanks! I published another puzzle called "royal romans in the fog" shortly after this one. I suspect you might like it.

[@arnodus70]

It would help if the num pad was shown the whole time in the video.

[@jonlittle5032]

Loved it! Only took me 2 1/2 hours! Thank god ctrl-z works.

[@realZahmet]

I'm a dumb dumb, but I love to watch these puzzels, yet when I heard both Chess and "this is a 3/5" I thought I'd give it a try. Took me 74:15, so very long, but it was fun, I got stuck at some stupid places (quite a bit at the end, since I had missed a simple fix for the 19 pair in the long Knight line, that could be resolved due to chess), but I was very nice to get some logic going and say to myself "this must be z since it cannot be x or y, due to chess and suduko" I had a blast, nice to see a puzzle that was approachable even for me.

[@LednacekZ]

21:56 for me. quite easy for a new rules set.

[@colej.banning2419]

Simon's accent being what it is, every time he said "pawn line" I imagined him saying "porn line."

[@SheilaMertens]

Beautiful puzzle! Not too hard either, when you know your chess moves that is. Either way, I would recommend it to everyone!

[@srwapo]

45:53, that I took to coloring odds and evens and it worked is super impressive. I didn't have a screwup with the kings line in box 6, after learning it had to go from 7 to 4 or 9, I started treating it as only able to move orthogonally and ruled out too many digits from r5c8.

[@Archik4]

You already said that column 2 use all odd digits. So the second bishop can't be odd.

[@DrBiscotti]

Question for Simon: You have a numberpad on your keyboard. Why don't you use it since you always struggle with the row above letters?

[@nightwishlover8913]

Also one on the screen...

[@mirandawilde5681]

I had a cat named Knight. We lost him to old age problems a few years ago. We got new kittens a couple months ago, a pair of brothers, also tuxedos like Knight was, so we named them Rook and Bishop. They are interested in this video. :)

[@jacobclaassen6565]

I colored even and odds. A knight move always changes chirality and bishop need to keep chirality, easy way to see that bishop line was odd, and then the other one had to be even because odd would break the rook line.

[@stephenbeck7222]

I agree that coloring could be helpful here. But I think parity is the more commonly used term for distinguishing even and odd, not chirality (for which I couldn’t find a number theory definition).

[@GreenMeansGOF]

Maybe we could replace the king in box 2 with a pawn and still get the same solution. That way there aren’t two white kings.

[@immanuii]

Took me 55:55 to solve! Incredible puzzle, seemed almost impossible for my level of skills at the start, but then it started to fall bit-by-bit

[@JohnGottschalk]

Complicated, but quite interesting!

[@koepisking]

This is a fantastic idea for a puzzle!!

[@MartinFindon]

Rather than looking at your keypad, why not just think of the Sudoku box numbers. Stops you from having to look down!

[@angec9908]

It blows my mind that Simon doesn’t use the number pad

[@biaberg3448]

But he does.

[@xdtjv2843]

Which one is it now?

[@xdtjv2843]

​@@biaberg3448Ok, he litterally says he doesn't usually use the numpad.

[@biaberg3448]

@@xdtjv2843 Oh, you meant usually to write numbers? Because he used it to solve this puzzle, he looked at it all the time.

[@xdtjv2843]

@@biaberg3448 Yeah, he normally fills in the numbers using the top display, not the numpad, but ofcourse in this puzzle the use of the numpad is forced.

[@andersl3415]

At 22:17 the 1 is removed from r2c8 because 7 can't go in r2c6, I can't get my head around that logic, can anyone explain? (removing 3 makes more sense to me)

[@RealCadde]

EDIT: OHHHH I am missing something... This comment is WRONG. King can move from 4 directly to 2. So ignore. 8:20 It would be more helpful to you if you spotted that you have an X-wing on fives in boxes 4 and 5. Thus eliminating 5 from R5C7. And so the next cell in the king line is from 179 and the final cell on the king line is from 4268. This because the king line cannot have a 5 on it because of the x-wing. So the king line alternates between odd and even digits. And it cannot reach the digit 3 in three moves from 7. Here's a list of possibilities. starting in R5C7. 478 874 412 896 The king will do one of those moves in that exact order.

[@malvoliosf]

Uh, in the UK, “pawn” and “porn” are pronounced the same.

[@NoobixCube]

Every Gundam fan got a Newtype shock at hearing it was Char's birthday.

[@mikerobutube]

Can anyone explain to me why at 25:03 Simon assumes the pawn sequence must be from 2-5-8? Could it not have been from 4-5-6? The rules say pawns can move up or down.

[@ouUnIXM1ASRQvM8u]

Up and down of numpad, 4-5-6 is left to right

[@erwintjia8586]

Oops. Sent before i could edit & enter my solution. I am sure my solution is correct because i have my conflict checker ON. I also repeatedly checked that i obey the given constraints.

[@nezarnassif2967]

Astonishing Puzzle, I feel very stupid compared to the minds that create theses sets of rules.

[@PassionPopsicle]

Yet another puzzle that seems SO interesting and right up my alley, that I probably won't try because I'm already confused just trying to remember the unusual rules 😂

[@jeffreytennant]

I agree. I prefer unusual logic to unusual rules

[@RecreationallyCynical]

19:13 for me. That was fun and interesting.

[@wanderlustwarrior]

1:13:44 for me. That was very challenging, but very fun!

[@wanderlustwarrior]

Take 2, got it in 37:13, with a lot clearer thinking.

[@salicus]

It took me VERY long to understand the rules :)

[@AndreAy1975]

Solved it without help from the video.

[@goffyBBBA]

Was anyone else tripped up by the fact that the Rook could wrap around and move from 1-7-9-3? I feel like I made assumptions based on not being able to do it?

[@Kirbyfan87827]

Finished in 36:02 with help from the video.

[@David_K_Booth]

Competed it without referring to the video, but took 52 minutes.

[@eddaumpeddaump4509]

I don't understand this rule set at all. I know sudoku but how the numbers operate seems to make no sense to