Battenburg Sudoku - 2019 R1 Puzzle 9

The rules as stated I believe are barely adequate, and could benefit from additional clarity.

The phrase "Everywhere 2 odd and 2 even digits form a 2x2 chessboard pattern, a Battenburg marking is given".

To someone who had never seen this puzzle before a very important fact crucial to solving the puzzle is obscured: namely that every 2x2 square of the grid which does not have a Battenburg marking also carries a lot of information - i.e. you cannot have the 2x2 odd/even checkerboard arrangement where there is no marking.

I heartily encourage competition directors and authors alike to be more friendly to new solvers who might already be overwhelmed by a variety of new Sudoku variants.

The same goes for many other variants, where the lack of marking is as important, if not more important than the markings that give the Sudoku variant its name.

E.g.

- XV
- Consecutive
- Kropki
- etc