Bizarro-doku (w/ MathGuy_12)
(Published on 24. October 2025, 21:24 by ThePedallingPianist)
It's been a pleasure working with MathGuy_12 on this puzzle - he really is a kind and clever individual, and I must credit him with the original idea and much of the execution! This is our response to Scojo's setting prompt of "parity mirror" from a couple of weeks ago, as redeemed by Calvinball. Many thanks to LMDemasi and NEWS for their world class testing services.
Doppelgänger Sudoku:
• Fill each cell of the main 9x9 grid such that every row, column and 3x3 box contains a 0 and eight different digits from 1-9;
• No two rows, no two columns and no two boxes may be missing the same digit;
• For each 0 in the grid, the digits missing in its row, column and region must be three different digits;
• Fill each outer cell with the digit missing from the corresponding row, column or box.
Anti-Parity Mirror:
• A pair of cells within the main 9x9 grid reflected to each other over the red line must contain digits of opposite even/odd parity.
Local constraints (standard):
• Digits along an arrow sum to the digit in its bulb;
• A white dot separates consecutive digits;
• A black dot separates digits in a 1:2 ratio;
• An X separates digits that sum to 10;
• A V separates digits that sum to 5.
Solution code: The column missing 9, top to bottom (9 digits)
Comments
yesterday, 19:59 by bodemeister
Very nice ideas here! Antiparity works so nicely with doppelganger!
on 12. December 2025, 21:32 by valacd
Why is there no difficulty rating above 'very hard'? this was exceptional (in both, difficulty and ingenuity). We got stuck hard several times, but what a fantastic puzzle. Thanks for setting!
on 12. December 2025, 21:28 by WildEnte
As so often a teamwork solve with valacd. We can now proudly state that we have solved a 7 star puzzle. What a beast! We learned a lot in the process.
on 31. October 2025, 16:02 by War
How are there so many solves? This was a (great)challenge. Break in was especially tough, but once I could use more zero logic things fell nicely into place
on 30. October 2025, 10:18 by wullemuus
Congrats to this really creative use of the Doppelgänger ruleset! It fits unexpectedly well with the Anti-Parity mirror logic. Also the other clues were used cleverly. Great job!
on 25. October 2025, 15:45 by bboom
Man that was some ride. I thought I was getting a bit quicker with solving 5 star puzzles, but this one took well over 4 hours. Never really became frustrating though, always so many little things to look at, and connections to keep in mind. Great job setting, the parity-mirror combined with the doppelganger is real fun, and probably deserves another puzzle or two, ideally slightly more approachable...
on 25. October 2025, 14:10 by yellow
wow,this was absurdly cool. great collab!
on 24. October 2025, 21:54 by lmdemasi
Achievement unlocked: convince ThePedallingPianist to add a clue to the grid.
