Standard sandwich rules - the numbers outside the grid equal the sum of the digits between 1 and 9.
Magic - Three of the 3x3 boxes form magic squares (each row, column, and diagonal sums to the same number). The 3 boxes are to be determined.
Solution code: Enter all the digits in row 3 then row 8, in order, with no spaces.
on 28. May 2020, 01:34 by Sam_CTC_Fan
Just adding Sudoku label
on 27. May 2020, 21:30 by JGLP
I legitimately love the logic in this sudoku, its among the best sudokus that I've solved.