Logic solvable
Dutch Flat Mates
Inspiration for this type comes from Flinty.
Solve online in Penpa+ or in Sudokupad.
Like all of my sudoku variants, this puzzle can be solved by logic alone. Guessing is not required and also no sophisticated solving techniques are necessary; just plain and easy sudoku steps and of course the intrinsic logic this specific variant has to offer. In case you don't find that logic or get stuck, feel free to ask for a hint in the comments below this puzzle and I'll be happy to help you.
Apply classic sudoku rules.
Every digit 5 has either a 1 directly above it, or a 9 directly below it, or both.
Solution code: Row 6
on 21. February 2025, 22:45 by Rollo
Flat Mates bringt immer wieder viel Spaß! Danke an Flinty und Richard.
on 21. February 2025, 21:33 by sujoyku
Phew, this was definitely harder than 2 stars for me. It is a very nice display of the great Dutch Flat Mates constraint. Thank you, Richard!
on 21. February 2025, 13:05 by goodcity
Really enjoyed this one, thanks Richard !
on 21. February 2025, 12:55 by Flinty
Lovely stuff. I'm honoured to get a nod in your epic series. I was intrigued when you commented about DFM on a previous puzzle whether you would pair it with another constraint(s) or do a 'classic'. Some tricky (2/5 level) steps in this puzzle in my opinion, but I really, really enjoyed it. Thank you. :)
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Thank you in return for the inspiration.
And I am pleased to read that you liked what I made out of this ruleset. :)
The nature of SVS is that every new variant I add has only one constraint. By combining rulesets, there would be at least 10.000 different working combinations of constraints, and I am sure my life would be too short to cover them all...
Besides: I am always on the lookout for suitable single constraint types to include in future championships or competitions. Being in charge for the Dutch Sudoku Championship, I like to add sudokus with an easy ruleset to my list of possible variants. When I start writing for a championship, I always go through my list of recent SVS's and many are too difficult as type to use. But this one is very likely to end on my wish list. The championship 2025 is already prepared, but for future episodes I am sure I will use it.
To conclude: After solving a bunch of DFM variants, I have to say that this is a variant that combines wonderful with many other constraints, so I can imagine your thoughts about whether I would use the classic variant or a comination. :)