Logic Masters Deutschland e.V.

For this Sudoku Variants Project I have planned to publish a unique Sudoku variant every week.
I will see how long it takes before I am running out of ideas.

Even X-Sums
Apply classic sudoku rules.
Clues outside the grid indicate the sum of the first X digits from that side, where X is the first digit from that side.
All clues with an even sum are given, although some clues are replaced with a question mark.
E.g. in case there is no clue outside the grid, the X-sum must be odd.

Inspiration for this type comes from 真笑.

Solve online in Sudokupad.