Argyle sudoku...

Argyle sudoku is a variant of sudoku (funnily enough) that has various additional regions.

The extra regions form a pleasant-looking criss-cross pattern. What is interesting about the extra regions is that they are partial - unlike something like Sudoku X they are not of length 9, in a 9-by-9 puzzle.

Therefore there are slightly different bits of logic that you can use to help solve these puzzles and that makes a pleasant change from ordinary sudoku, in a similar sort of way to the way that you use partial elimination logic when solving puzzle types such as isosudoku that also have some partial regions in them.