Erica 21 (Phistomefel Ring Edition)
(Published on 4. December 2025, 17:15 by SennyK)
You will need to notice tricky things to solve today's Erica :-)
I hope you will enjoy and I would be really grateful for all the comments and ratings.
Normal sudoku rules apply.
German whisper: Neighbouring/adjacent digits along a green line have a difference of at least 5.
X/V: Digits in cells joined by an X sum to 10. Digits in cells joined by a V sum to 5. Not all Xs and Vs are given.
If you liked this puzzle, I recommend trying out my other puzzles: The Erica Series:★☆☆☆☆: 1, 2, 4, 5, 6, 12, 15, 17, 23, 26, 27
★★☆☆☆: 3, 7, 8, 10, 11, 13, 14, 16, 18, 20, 24, 25
★★★☆☆: 9, 19, 21, 22 Shading/Ying-Yang:
★★☆☆☆: Pretty Odd Shaded Area
★★★☆☆: (+5)-Yang, Negative 8 YY
★★★★★: Why-Why? Fog of War:
★☆☆☆☆: Erica 12, Erica 17
★★☆☆☆: It's What You Do in the Dark That Puts You in the Light, Find It All, What the Fog?, Erica 20
★★★☆☆: Broken Flashlight in the Dark Pencil Puzzle/Sudoku Hybrid:
★★☆☆☆: Masyu (Short) Sudoku
★★★☆☆: Tetromino Sudoku
Various Puzzles:
★☆☆☆☆: Blown Fuses in Electrical Installation, Let Me Introduce Myself, French Wrench
★★☆☆☆: Symmetrical Fan, Night Club, Important Hour on the Clock, What Was the Sum Again?, Disgroup Joints, 10-Arrows, Antiking Dutch Skyscrapers
★★★☆☆: Cops & Robbers, Positive Symmetry, Doppelgänger Killer 1-25
★★★★☆: Liars. Liars Everywhere.
Solution code: Ninth (9th) row of the grid from left to right.
Comments
on 16. January 2026, 09:36 by sunevora
Could not see how the Mephistophel Ring gives any advantage here.
on 6. December 2025, 16:07 by Ste1729
This puzzle is probably 1* if you're familiar with Phistomefel ring, but it's 3* otherwise.
I didn't know about Phistomefel ring, and I started solving normally. After around 1 hour, (I had only placed 8 digits) one of my friends joined me, told me that rule and together we finished the sudoku in just 10 minutes.
on 6. December 2025, 08:30 by Snuggles
I found phistomefel useful in this solve
on 6. December 2025, 06:02 by VitP
anyone claiming this is a 5 min puzzle, or level 1, is either trolling, or worse.
there ARE a couple of easy steps that break this puzzle open, but actually FINDING them without extensive testing - not going to happen.
other than that, as long as you use standard gw procedures plus basic sudoku, it's straightforward.
phistomefel gives no advantage.
hint: the 67 pair, and the row 7 4s
on 6. December 2025, 03:20 by QuiltyAsCharged
I had to find some pretty subtle things to break the symmetry of the grid. Nothing overly difficult, but I'm surprised to see people saying it could be 1* difficulty! Very nice puzzle
on 5. December 2025, 21:21 by APigthatflys
Nice set as always, although I didn't fond myself needing to use The Secret at all. Just took a keen eye and lots of colouring
on 5. December 2025, 21:09 by UnknownDjinn
I'm new to variant sudoku. I normally stick to 1 or 2* puzzles. I would say (maybe because I know of the Phistomefel Ring) that this puzzle was on the lower side of 2* maybe even 1*. I had a great bit of fun solving this though. Thank you for the treat!
on 4. December 2025, 18:59 by PinkNickels
Really fun, but it took a bit over 5 minutes. I would say this is a 1*. But still very nice! Maybe a 2* if one isn't familiar with the secret?
on 4. December 2025, 18:46 by Martina
Very nice!
