Can You Follow The Traces?

Cosmic-class construction. 👏👏👏👏👏👏👏👏
Ruling 9 out of r1c6 was quite challenging for me, but since the logic was beautiful it was well worth the effort.
Also, my way to perform that deduction was the same as Simon's, but now I know there is a slightly easier way, as described, for instance, by HunterJE and mstmar in this section.

Is the 3 clue actually needed to solve this puzzle? Once you get a 7,2 domino in box 5, as long as you've coloured and pencil marked all the 8 dominos accurately, you discover which 10 domino is which in box two. That automatically puts a 3 in the domino directly above the 3 clue.

I could be wrong, but I was getting worried towards the end that I simply couldn't see the purpose of it.

I finished in 113 minutes. This was a long one, but quite fun. I think my favorite part was realizing that one of two cells, r4c1 and r9c6, had to be a 9. Therefore, r4c6 couldn't be a 9 and had to belong in box 1, making those region sums add to 10. Great Puzzle!

I found this pretty tricky, but there was some lovely logic so I'm happy I persevered.

damn, that was a hard one! really enjoyed it, thank you

its not often i can see logic faster than simon, but the moment the 9 appears in box 9 we can tell that the other set has to sum to 8

When you were looking at 9 in box 2 you didn’t look quite hard enough at box 7. It would have been less difficult. But still a challenge. Also I love this puzzle and the video!

Blooming marvellous

Solved it with much help from the video.

Brilliant puzzle.

Not checking immediately what happens when green is 37 has made me very disappointed when I watched Simon's solve...

I was yelling at the screen for ages that grey had to be a 3 7 pair. Because whether or not the three was below the circle or not grey always had a 3.

Beautiful puzzle, I saw more than I usually manage to

"Rose, your wife Bee wrote to us"

99 minutes

Thanks for the (slightly early) birthday shout, Simon! And for another fantastic puzzle to solve! 💜

This puzzle is great. You can't fake it.
It must have been tricky to make it.
And my good Arbitrary,
It has made me quite merry,
For I never once managed to break it!

My starting observation was slightly different. I realized those 8 digits he is talking about had to be all different. Therefore they all add up to 45 minus a digit. The total had to be divisible by 4 because of the 4 segments. So they summed up to 36, 40 or 44 and the "1" clue eliminated the possibility of 44. And that's as far as I got.

Does anyone else get slightly disappointed when there's no 3 in the corner? 😂

You spent a lot of time on the r1c3 r2c3 domino but as soon as you knew it was 10 you could prove it was grey very easily.

If you had arbitrarily assigned orange and yellow to dominos in box 2, then the one in the top row would be ruled out immediately and you also would have had two of the same colour looking at r2c3.

And the same logic would hold if you swapped the colours.

85:02 for me. I made excellent progress and loved the deductions but got horrifically stuck after placing 10 digits in. The question I needed to ask that broke everything wide open afterward was "what value can r3c1 actually have?". You use the 3 quad clue to rule out one of the options, and the rest of the puzzle is pretty straightforward after.

Edit: I watched up to the point where Simon figured out what r3c1 was. I did the logic backwards to his solution. I considered whether the cell could be 3 and found it would put two 8's in row 4 (one because of the sum in col 1 and a 2+8 in box 6 forced by the 3 in the quad).

Can we appreciate Simon explaining "the secret" every time it comes up, instead of just assuming we've seen other videos and know? It just makes these videos so much more approachable to someone that just catches a single video, they still get to learn something.

Amazing! I can't believe that I could solve this one!!! It take me 70:27 to do this, but it was worth it. I had a resolution today: I will solve this yes or yes! No looking for hints! And I did it! 🎉🎉🎉

Thanks for the solve Simon! I usually would only watch you, but today I am quite happy about my solve as well! 😀

Ah thank you for the happy birthday! ☺️ 10/10 we had chocolate cake

This puzzle is a brilliant masterclass in pointing pairs and x-wings.

I am shocked that Simon can't figure out the simple reason that R1C6 can't be a 9. If it was, you have to get value of the other line segment to add to 8 two different ways which is impossible with the values you need to add to 10 in that box. You have to use 2 combinations of 2,8 3,7, and 4,6 in the green and grey squares, but that leaves you with not enough ways to make 8 since if you use the first and second, you only have gotten rid of every possibility 1,7 2, 6 and 3,5: if you use the first and 3rd ones, you have gotten rid of 2,6 and 3,5 and if you use the 2nd and 3rd ones, you gotten rid of 1,7 and 2,6!

Does anyone else find it extremely condescending when Simon mocks us with his "very best friends" speech?

Simon the other green in box 1 must go in row three. This makes a 2378 in row 3 and cell 9 in box 3 must be a 5.

Brilliant puzzle. Brilliant solve.

63:40 for me

Finished in 67:57 and just got pipped by Simon. Took me a while to get going with this puzzle as I'm not very good with most line puzzles. I went down the possibilities in box 2 but it turns out the first one I went down was the correct solution, so I couldn't find a contradiction, but as I worked through it, I realized that 1 of the quad circles became very important which allowed me to eliminate the other possibilities and restart the correct possibility and finish it.

Fun puzzle!

Usually, when it takes Simon more than an hour to solve a puzzle, I find myself unable to even start or otherwise get completely stuck, but I managed to solve this AND even faster than Simon! I never thought this day would come 🎂🎉

the digits moving isn't new. It's been that way for a while.