it's easier to copy puzzles than to create them..
This is yesterday's difficult 4x4:
https://www.sporcle.com/games/Joshie_th ... =dH6814598The one before that in the "Calcudoku playlist" is the difficult 6x6 of November 12th,
with one puzzler commenting "this is the hardest one so far, by far.". Indeed
"sporcle" says it's the "World's Largest Trivia Quiz Website"
I don't mind so much the puzzles being posted, but a reference to the source would have been nice