In addition to standard Sudoku rules:
Links: F-puzzles, Sudoku Exchange
Solution code: Row 4 followed by column 6 (18 digits)
on 14. June 2020, 01:13 by Rollo
Very nice idea. I had luck and came through while trying one number, so I can't rate the difficulty.
on 14. June 2020, 00:04 by jcreed
My actual solve time was around 3h. Especially enjoyed the initial phase of this one, figuring out what to do with the constraints.