Field Research Into Fog Sudoku

*** TODAY'S PUZZLE ***
ChinStrap's puzzle, Field Research, combines dynamic fog-of-war sudoku with index lines (beloved, apparently, of computer programmers). This puzzle deserves a LOT more plaudits - it's inventive and brilliant. Don't miss this one!

Play the puzzle at the link below:

Rules:
Normal sudoku rules apply. The grid is covered in fog. Placing a correct digit in a cell lifts fog in that cell and possibly other cells; revealing new clues. On an “index line”, the digit in the Nth cell along the line (starting from the diamond) indicates the position along the line where the digit N appears. For example: 3214 would be a valid line with the 3 on the diamond; the 1st digit, 3, indicates that the 3rd digit is a 1, and so on. Inequality signs point to the smaller of the two digits. Digits separated by a white dot are consecutive. Digits separated by an X sum to 10. Not all such symbols are necessarily given.

Play Cracking The Cryptic Bingo thanks to Marushia Dark here:

*** LAST WEEK'S STREAM ***
You can watch the continuation of our battle with the Caterdokupillar here:

*** DECEMBER'S SUDOKU HUNT COMPETITION ***
The solution videos for December's monthly competition "Swipe Right" will be released imminently. The competition winner will be announced shortly and be given the chance (but not obligation!) to make a sudoku video with Simon.

On 1 January we have a brand new sudoku hunt from Blobz, the 'sequel' to his Lord Of The Rings hunt earlier this year... The Hobbit!

Check it out for as little as $2/month here:

*** NEW FOG APP IS OUT ON APPLE (!), STEAM & ANDROID ***
Brand new incredible Fog Sudoku puzzles by the likes of Phistomefel, Marty Sears, James Sinclair, Qodec, Dorlir, ThePedallingPianist, Sandra&Nala, Peter Veenis, Mr Menace, Florian Wortmann, Math Pesto & HalfBakedLunatic.

*** CRACKING THE CRYPTIC APP ***
Our main app (which is itself completely free) contains packs featuring Fog, Domino, Lines, and GAS puzzles, with a few special free sets as well! All the puzzles are hand-crafted by us and some of the best constructors in the world, with hints by Simon and Mark.
AppStore:
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ALSO on Amazon: Search for “SudokuPad”

▶ Contents Of This Video ◀

0:00 Intro music & puzzle introduction
1:45 Our New Fog Sudoku App
1:58 Blobz' The Hobbit sudoku hunt
2:50 Happy Birthdays
6:07 Rules
9:06 Start of Solve: Let's Get Cracking

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#sudoku #puzzle #index

[ChrisNeffshade]

ChinStrap here. Thank you for the great solve! Massively appreciate it.

The length of the index line is such a powerful piece of information that the allure of hiding that behind fog was an instant hook into setting this puzzle. Glad it turned out so well.

And yes the lack of diagonals were meant to be understood under the fog by the fact that i made the lines so thick. I even included an opening line with a diagonal so you could see how much sticks into adjacent boxes when it moves diagonally.

[George]

In the initial break-in, at around 12-14, there are some "tricks" to index lines that are not mentioned. Either a digit indexes itself (is singleton) or is part of a reflective pair. They each are Renban lines containing a 1 because some digit must appear in the diamond saying "I'm first." A 5 in the diamond places a 1 in position 5. All must have the digits 1 to N where N is the length. An odd length line has an odd number of singletons. An even length line has an even number of singletons.

[martysears]

Absolutely brilliant puzzle, the dynamic fog was handled with the utmost expertise

[katiekawaii]

37:05 Why not? I imagine setters probably take a lot of care to consider the grid furniture and how it's revealed. It seems wrong to ignore that. To any setters in the comments: I'd love to hear your opinions.

[windybeach]

Simon, I’m always thoroughly impressed by your ability to pinpoint exactly where you made an error. When I mess up, I usually have to restart the whole puzzle to be sure that my logic is correct.

[davidblake]

Fantastic puzzle! It is definitely the most difficult FOW I have ever solved. Watching Simons solve afterwards made me feel great empathy. Especially when he stumbled in exactly the same places in the logic path that I did. At least I made different errors in my solve due to incorrect pencil marks. Thank you, Chinstrap. You have made my Sudoku year.

[longwaytotipperary]

So good to have Simon solving a foggy puzzle on a foggy day!

[izzynicoli]

Love watching these to fall asleep, and just as I'm about to drift off I heard your overwatch reference at 1:06:15 ish and now here I am, fully awake and surprised you knew about widowmaker!

[emilywilliams]

A very interesting puzzle, and I enjoyed your video, Simon. One of the things you and Mark have taught me is not to over-pencil-mark, which I think that you sometimes under-pencil-mark - but I think you struck just the right balance in this solve. Thanks for this video during the holiday season!

[mcs]

Love the puzzle!

Another shameless ask / suggestion for the app if there's ever bandwidth: It would be nice to be able to turn off the "defogging" - to be able to mess around / mark things up without accidentally revealing.

Thanks!

[penningmeestercgkdelft]

53:58 Simon, although I shouted a lot to the screen about placing the 6 in r4c4 (just by indexing logic), I am always very impressed how often you manage to repair any error if the puzzle seemed to be broken. Your correction of the pencilmarks is just spot on!

[markp]

30:48 finish. I second guessed myself at the beginning when fog wasn't clearing, but I soon realized as Simon did that it was just teasing us. An excellent puzzle, fun fun fun!

[jonathancard]

Very foggy here in Boston, too. Must be why it's called New England.

[SVURulez]

I was "solving along" with the video on in the background, keeping about 5 minutes ahead of where Simon was, when he made the mistake in box 4 that caused me to panic and double check my solve. Was very relieved to discover it was his mistake and not mine!

[compiling]

Solved in 31:37. Lots of really interesting logic to place a single digit in that one. Then it doesn't clear any fog, so you need to look for more logic with the existing clues.

The good thing about a well designed dynamic fog puzzle is it clears fog the moment there isn't any more logic to tease out, so you know when to stop looking.

[Pete]

At 44:22 Simon works out that what appears in R4C2 (the 4th position on the line) must be a 7, or 8. He could have used the same logic to work out that the only digit that could appear in R4C4 (the 6th position on the line) is a 6.

[cassidypacada]

Never thought I’d see an Overwatch reference in one of these solves 😂😂 Lovely video as always and a beautiful puzzle

[ericzache]

I like how my brain completed 0:23 with "no guessing required"

[grahamania]

00:56:07 for me. Probably the best index line puzzle so far. Loved it! Kind comment.

[daniellucas]

26:00 4 in column 7 can only be on the line, is the easy way to see this deduction.