Doppelgänger Warm-up
(Published on 3. December 2025, 06:47 by Andrewsarchus)
An approachable Doppelgänger puzzle.
Rules:
- Doppelgänger Sudoku:
- Fill each row, coloum, and box in the main grid with digits from 0-9 without repeats.
- Every row, column, and 3x3 box in the main grid must contain a 0, and must therefore omit one of the digits from 1-9.
- Each digit from 1-9 is missing from exactly one row, one column, and one box.
- For each 0, the digit missing in its row, column, and box must be three distinct digits.
- Three auxiliary grids are provided for recording the missing digits.
- The 9x1 strip below the main grid records the digit missing in the corresponding column of the main grid.
- The 1x9 strip to the right of the main grid records the digit missing from the corresponding row of the main grid.
- The 3x3 box in the lower right records the digit missing from the corresponding box of the main grid.
- Thermometers:
- Digits along a thermometer strictly increase from bulb to tip.
Play Online:
sudokupad: Doppelgänger Warm-up
Solution code: column 5 (main grid only)
Comments
on 9. December 2025, 12:42 by valacd
Felt very approachable. A great way to learn about doppelgänger puzzles (I got stuck in a very difficult one and figured I should try an easier one first), this puzzle taught me the tricks of a doppelgänger sudoku. Thanks a lot!
on 5. December 2025, 18:02 by teuthida
It actually felt like a approachable Doppelgänger, thank you for setting and sharing!
on 4. December 2025, 16:12 by bodemeister
Nice 8-minute run!
on 4. December 2025, 06:47 by Playmaker6174
To be honest, "approachable Doppelgänger sudoku" sounded like a fever dream to me at first and after solving this one, it still kinda is (lol) but this one was certainly much easier than most of the puzzle using such concept I'd solved x)
I like the fact that this puzzle still left enough room for solvers to exercise the basic scanning with the concept and didn't try to overcomplicate or trivialize that task too much.
on 4. December 2025, 01:30 by johnreid
Good fun, thanks!
on 3. December 2025, 20:32 by dzamie
Dunno what people are complaining about, this is very approachable for a mildly complex variant like Doppelganger. The 9-length thermos provide an excellent starting point (the extra box basically starts solved). While some knowledge of how the extra box and extra row/column values interact is helpful, I don't think it's necessary.
Plus, the puzzle makes good use of the "a 0 replaces a different number for its row/col/box" rule. It's easy to forget, and in my solve, I managed to get a lot of the puzzle filled before absolutely needing to use it - this makes the most complex part of a Doppelganger relatively simple compared to other puzzles with the variant.
--
lol - only VitP was actually complaining. The other comments are making fun of VitP's assertions. :-)
--Andrewsarchus
on 3. December 2025, 20:07 by TVDK
THIS puzzle is a LEVEL 2 despite it being an ENTIRELY NON-INTUITIVE variant. As a FIRST solve of this variant still took less than 15 MINUTES. This INTRACTABLE puzzle was VERY NICE to solv- I mean- BIFURCATE.
on 3. December 2025, 19:46 by Black_Doom
An EXTENSIVE research showed that a sudoku EXPERT needs ONLY 14 minutes of bifurcation to complete this SLIGHTLY less than COMPLETELY intractable puzzle that utilizes an ENTIRELY non-intuitive variant.
on 3. December 2025, 19:22 by aqjhs
"approachable doppelgänger" = this.
why?
because:
- it uses the well established clue type that thermos are in a straight forward manner.
- features the logic of the doppelgänger setting in a non trivial and interesting way.
- allows for a solve path that increasingly involves that doppelgänger logic.
QED.
on 3. December 2025, 16:51 by VitP
translation:
"approachable doppelganger" =
"slightly less than completely intractable"
why?
because:
- ordinary sudoku patterns are almost completely useless
- the variant is entirely non-intuitive, and does not correlate to any common variant
- absent any existing foundation, hours of bifurcation will be required, just to learn the basic patterns
-
on 3. December 2025, 09:45 by SennyK
If you are not familiar with Doppelgänger, this is a perfect puzzle to start your adventrue with this fun sudoku type, really approachable!
on 3. December 2025, 09:41 by Piatato
Smooth!
