Greater Doppelganger
(Published on 15. January 2022, 17:54 by Kafkapharnaum)
DOPPELGANGER RULES
– Every row, column, and box contains the digit 0 always, as well as eight out of the nine digits from 1 to 9 (ie, it's missing one digit that is not 0)
– No two row, no two column, and no two box may be missing the same digit
– For each 0 in the grid, the digits missing in its row, its column, and its box must be three different digits
ARROW SUDOKU RULES: Digits along an arrow sum to the digit in the connected circle. Digits may repeat along an arrow if permitted by the other rules. The 0's always count for nothing (zero/null) in the sums
You can find a 4x4 example of how this concept works on the page of my first puzzle on the site (using killer clues), and obviously you can solve that (much easier) puzzle too beforehand to get a feel for it
SOLVING LINKS (no solution check)
Solve on Penpa (w/tracking cells)
Solve on Penpa (main grid only)
Solve on the CTC app (w/tracking cells)
Solve on the CTC app (main grid only)
TIP (to keep automatisms in check and prevent frustration, really):
It will likely be very tempting at times to see as a 'write-in' a digit that say, has only ONE place where it can go in a row, or a column. DON'T WRITE IT IN JUST YET UNLESS IT HAS ALREADY BEEN PROVEN TO BE MISSING IN ANOTHER. There is always the possibility that it will actually be MISSING in that row, box or column, and since it is not there, the other digits/candidates will be left unaffected
Solution code: Row 3, Column 3
Comments
on 29. July 2024, 14:17 by sanabas
Great fun, and the constraint requiring 0 to miss three different digits was very important in a couple of sections. Into the red it goes, too.
on 25. February 2024, 17:16 by bodemeister
Hopefully we can get this beast a red rating soon! Beautiful design and harder than I expected. Thanks for the puzzle!
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Yes, I think that even as my very first of my 'personal challenges to myself' and dating from over two years ago now, that it still hold up quite nicely, no? Anyhow, I'm glad you enjoyed it, and huge thanks again for the streak of solves on these puzzles and overall support! :D
on 14. August 2023, 13:27 by wullemuus
Another one solved :D! It needed three attempts to find the right way (that time I solved r6c9 earlier) because of the arrow construction (what I normaly avoid) and the rest was as you described it. So most I've learnt was how to solve arrows more effiently ... . The zeros were the fun factor :D. Thanks!
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I gotta say, it's quite thrilling to see these notifications every morning, I'll miss it where you've slain the last one of these 9x9 Doppelgangers of mine! Each and every one of these puzzles took me weeks, when it's not months to set, so I really do mean it when I say each solve on them is very special to me, thank you so much!
Now, if you intend on going the full distance, well I imagine you looked already, but the others aren't so obviously advertised as 'Doppelgangers', as they are hybrids with other original rulesets. I have:
- Atlantis (hybrid with Coordinate Arrows)
- Suspended Animation (hybrid with Still Life)
- Nevermore Samurai (Mega-hybrid with both of these + 2 other rulesets)
THen there's 007 (possibly outdated a bit at this point, but close to a rating!), and the 'tough little buggers' -- Parcae, and the Nanodoppelgangers, which can still pose a challenge I think, so, plenty to choose from! THanks so much again, I'm happy you're enjoying this trail! :D
on 7. August 2022, 00:18 by Samish
What an extraordinary puzzle. Took me ages but with my training at your other easier doppelgangers, I didn't make any mistake and didn't feel at risk about that. It needed a little exploration at some points (the way I solved it), but once I accepted to go that way, it was always very intuitive as where to look, and the solve went unexpectedly smooth, which makes me say the construction is amazing ! I'm very happy I managed to solve this one !! :-)
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Thank you so much for such kind words! Like I said quite a few times below, every solve on this one is very special to me, and all your other solves and comments on the other 'Doppelganger' puzzles are very heartwarming too. This is a very big encouragement in trying to develop this ruleset some more! :D
on 26. June 2022, 22:50 by polar
Wonderful puzzle with a very fun (but very tricky) ruleset! I managed to break it a couple times and honestly I have no idea which deduction(s) I made that were wrong, but it was no less fun on the 2nd and 3rd attempts. Thanks :)
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My goodness Polar, you have been on an absolute tear this weekend in Sktx's puzzles and mine! This is more appreciated than you know, and you are definitely getting personally thanked in a future upload! :D (And additional thanks for the kind words on this one here :-)
As for breaking it, being the godly solver than you are, I imagine you didn't look at the 'tip', but a common error with this ruleset (which still happens to me as the setter XD) is treating a digit that *could* be in a box (+ corresponding row or column) as if it's *definitely* preventing it from appearing in the same row or column in another box. But if it turns out it's NOT in the first box at all, then it's free to appear in that row/column in the other box. This comes into play in this puzzle, so I'd imagine it was that. :-) In any case, congrats for the solve, and huge thanks again!
on 22. March 2022, 10:51 by Piatato
Amazing construction. Although I now am starting to get a bit of a grasp on this ruleset, I still have no idea of how you would go about setting this. I enjoyed figuring things out — it definitely was intricate, yet I still found that the logic all in all was surprisingly clean.
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Thank you so very much again for your solve on this one! This is by far the puzzle I spent the most time setting, and so every solve on it is very special (though all solves - and indeed just attempts - are appreciated of course)
And now that I've shared my secret, I've no doubt you'll leave me in the dust with your next creation, but I'm still very eager to see what you'll come up with, even if I can't solve it XD
on 27. January 2022, 03:51 by jgreenfield
This is a beautiful puzzle, though it certainly takes some work to get through it. Well worth it in the end -- once you get past a certain point, everything falls into place and it's a smooth solve from then on.
I also used two tabs to keep track of everything, as well as a whiteboard/dry-erase marker for parallel analysis of possible combinations. Seeing the possibilities side by side was immensely helpful for my solve path, though it isn't strictly necessary.
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Thank you so much for your solve! Every single solve on this one is immensely appreciated, as are your kind words, of course, and overall interest in these 'Doppelgangers' puzzle :D
on 17. January 2022, 19:50 by pwfd
This was the hardest puzzle I ever solved, loved the doppelgänger constraint, but this was very hard, openning both penpa and CtC helped a lot (penpa for keeping track of the tables, but doing the actual puzzle in CtC).
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Wow, thank you so much for that comment (and for your solve, of course) -- makes me all the more happy to hear that you found the two tabs method using the CTC app useful and that it worked exactly as intended!
on 17. January 2022, 12:54 by Elliott810
Very nice and very hard puzzle, a real challenge. Lots of possibilities to go wrong. Even now after finishing the puzzle I can't claim, that I've really internalized the rule set. First puzzle where the solution code itself is a puzzle;) Thx for sharing:)
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Thank you so very much for your solve! I was saying below I'd be happy if this one got even just one solve, well, it has one now and I'm very happy!
Incidentally, I recognize your name from seeing it in the list of solvers of my '007' puzzle after I thought about linking this one too --- so really, thanks a thousand for the time you spent on my quirky variant!
on 17. January 2022, 04:45 by Playmaker6174
So if I understand it correctly: 0 also follows normal Sudoku rules, for each box(/row/column) 0 replaces one digit from 1-9 once and for all instances, 0 in terms of value counts as a 0.
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That's exactly it! I'm so sorry it was not clear -- if you check my first puzzle (linked in the description), you'll find an example and more detailed explanations, which I thought were too wordy and fanciful, but as it turns out, maybe they were better afterall... Thank you also for your interest! :-)
on 17. January 2022, 00:26 by SudokuExplorer
When a zero lies on an arrow, what value does it take?
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It counts for zero (nothing)! I'm so sorry, this time with this variant I wanted to be as succinct as possible in my explanations/rules to not put off anybody from trying, but I think I might have actually shot myself in the foot there... In any case, thank you for your interest in this puzzle! :D
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Aha, thanks for clarifying! I've put it in my observation list so will try it hopefully in the near future. :-)
on 16. January 2022, 01:41 by filuta
oh, hi, happy to see you back, I hope I will get to this one soon, because it looks incredible (but probably will need at least a free weekend to even attempt it seriously)
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Hello! Yes, I don't expect anybody to solve this in a single session, and this time, in all honesty, I'll consider myself happy if I get even just one solve on this one!
By the way, I've been attempting your Build Your Own Samurai Sudoku during the holidays -- I haven't solved it (yet) but I think I've made good progress; it's really fun and I'm hoping to solve it soon! :D
