Makodoku
Inspiriation for this type comes from WSC 2018.
Solve online in Penpa+ (thanks Nick Smirnov!)
Apply classic sudoku rules. All pairs of adjacent digits with a product less than 10 are marked with a cross sign. All pairs of adjacent digits with a sum less than 10 are marked with a plus sign. If both signs are possible, a cross sign is drawn. If there is no sign between two cells, the sum and product are both minimal 10.
Solution code: Row 5, followed by column 5.
on 3. November 2021, 05:36 by Richard
Added link for online solving. Thx Nick!
on 24. October 2021, 22:12 by Nick Smirnov
Penpa:
https://git.io/JiG5D
on 26. March 2019, 15:53 by Mody
Das war schön :)
on 26. March 2019, 06:56 by Richard
fixed typo in the title