Easy Peasy Sudoku Advent (16) - Y-Sums
(Published on 16. December 2025, 06:00 by Richard)
This sudoku advent calendar contains 24 variants that were included in my Sudoku Variants Series (SVS) but turned out to be too hard to be solved by a wide range of puzzlers. I aim for difficulties of 1-2 stars and have written some general and/or specific hints as well. I hope some players will try the original SVS puzzle #302 after solving the advent version.
Y-Sums
General hint for this type:
The small clues have limited possibilities.
For the 3-clue there is only one possibility (3->1). If you try to count two cells, there is no place for the 2.
Apply classic sudoku rules.
Clues outside the grid indicate the sum of the first Y digits from that side where Y is the Xth digit from that side and X is the first digit from that side.
For the 6-clue above C7, there is now also only one possibility (6 ->1), and after that, the same goes for the 6-clue above C6 (5 ->2).
The clue of 44 means that only 1 is outside the count, hence R1C1 is 1 and eight cells are counted. That means the 8 is not in the eight’ position (C2) and also not in the first position. Because of the placed digits in R1C678 there is now only one place that that 8 can go to.
For a 5-clue there are only two possibilities at all (4 ->2) and (5 ->1).
Solution code: Column 9
Comments
on 23. December 2025, 09:42 by Phase Queen Rachel
Made a bad assumption in Row 4 and got stuck for like 30 minutes, but eventually figured out my mistake and solved the puzz. Very fun break-in, wish I could have kept the flow going but alas...
on 19. December 2025, 12:43 by SennyK
Very creative and fun! :-)
on 18. December 2025, 09:32 by AnnaTh
Needed the hidden hints for the first time
:-)
on 17. December 2025, 09:36 by Fra314
This puzzle confirmed my complete ineptitude for mathematics. But it's good. Very good. VERY VERY GOOD.
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Reply: haha, thx. THX. THX!!
on 17. December 2025, 06:32 by Crusader175
Loved this variant and fun introduction puzzle!
on 16. December 2025, 20:51 by Klausku
Brain-twisting ruleset. But after the first steps, it flowed quite smoothly. Thanks.
on 16. December 2025, 19:55 by dzamie
A pretty intimidating rule, but a surprisingly approachable puzzle for it, including a few really easy Y-sum clues to get started before the challenge begins.
on 16. December 2025, 13:28 by Franjo
Again a lovely introduction for this constraint, which caused some headaches in the past. Thank you very much for creating and sharing this puzzle.
on 16. December 2025, 09:37 by Piatato
Great fun, thanks!
