Shadowgate
(Published on 16. June 2025, 01:40 by Kafkapharnaum)
RULES
DYNAMIC FOG
• The grid is covered in fog. Entering correct digits or sets of digits might clear fog somewhere in the grid. No guessing is required.
• Cells outside the grid (the 'tracker cells') may sometimes need to be filled to clear additional fog.
DOPPELGANGER
• 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 a 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, such that a zero cannot replace the same digit more than once, and yet zeros always have a null value (ie, zero).
LINES
• The grid contains Region Sum Lines, colored blue and thinner, and Renbans, colored purple and thicker.
• The lines in the puzzle do not branch, such that any cell can only be connected to a maximum of two other cells by a line, and two lines of the same color cannot share the same cell.
— REGION SUM LINES
• The 3x3 box borders divide each blue line into segments of the same sums. Different lines may have different sums.
— RENBANS
• Digits along a purple line must form a sequence of non-repeating consecutive digits, which can appear in any order.
Play the puzzle on Sudokupad
fog of war FoW
Solution code: Row 5 (from left to right, main grid only – 9 digits total)
Comments
on 19. June 2025, 23:44 by StephenR
Excellent and innovative puzzle, thanks. Messed with my head a bit at first, but glad I persevered. This is definitely worthy of a CTC feature.
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Wow, thank you so much for this comment, that is very pleasing to hear and I really appreciate it, as I must say that I was a bit worried when I set this puzzle that I had made some requirements between sections a little too stringent or exhaustive, such that it could maybe cause some solvers to start doubting some of their deductions, and I am glad to hear that it didn't stop you -- thanks again for sharing!
on 17. June 2025, 13:48 by Visumation
Great puzzle. Thanks
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Many thanks for the kind words, much appreciated - glad you enjoyed the puzzle!
on 17. June 2025, 07:52 by wullemuus
Very enjoyable!
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Heeyy, hello there! Thank you for solving this one that must be just a candy for you haha -- glad to hear you enjoyed it! :D
on 17. June 2025, 03:21 by abihummel
Absolutely amazing! The way the fog guides you through the deductions is stunning! This is what fog was made for!
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Ah, thank you so much Abi, your comment is very heartwarming as this was very precisely my whole reason of using this feature and really just of this puzzle as a whole; and many thanks as well for all the other kind words, I'm super happy you enjoyed the puzzle like that! :D
on 16. June 2025, 22:51 by Exigus
Delightful and smooth use of the fog. Thanks!
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Thank you so much for the kind words, glad you enjoyed the puzzle and its use of the fog! :D
on 16. June 2025, 12:56 by SudokuFan
You also need to add the rule that lines of the same color can't share cells, as the puzzle is unsolvable without that assumption
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Ah yes, good point - it was my very first use of the custom positioning and length of lines, and it didn't occur to me that even if two segments are aligned, that with this function they could still end or turn before reaching the middle of a cell they entered. Of course, one solution could be to simply remove more fog, but then the puzzle would lose much of its cheekiness, so I will use your solution instead, thanks for raising it up!
on 16. June 2025, 11:02 by chrisj50
Another lovely DG and delighted to see you venture into the Dynamic Fog! I think this would be a good puzzle for those new to this variant, as it certainly steers you along the solve path. Thanks as always :)
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It really is an incredible (and super fun) feature isn't it :D So far it looks like the puzzle is achieving its goal quite well, that's really pleasing to see -- thanks so much for all your feedback and help in coming up with this!
on 16. June 2025, 06:05 by earthpuzzles
These easier doppelgängers are a delight! I appreciated the no-branching rule, and the selective dynamic fog reveals.
I’m curious whether how solvable this would be without the no-branching rule. I’ll have to give it a shot if I need something to chew on later.
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Ah, thank you so much for the kind words, glad you enjoyed it and its features, as well as Pychael's pack that I see you solved immediately before! :D
And it's an interesting thought about the branching, I hadn't really thought about it other than really trying to make things as smooth as possible, while still hopefully interesting. Let me knkw how it goes!
