What is X Sudoku? (Diagonal Sudoku)

X Sudoku is also referred to diagonal Sudoku. It is another type of standard Sudoku. Based on standard Sudoku, diagonal Sudoku has more requirements. Numbers on two sides of diagonal lines have to be numbers from 1-9 and cannot be repeated. Since diagonal Sudoku has more requirements, the solving process is more challenging and interesting. It also has more requirements related to players’ observation capacities.

The rules of X Sudoku (Diagonal Sudoku)

The solving process of diagonal Sudoku is to fill numbers from 1-9 in 9x9 grids. Numbers cannot be repetitive in each row, each column, each group (3x3 grids in rough-line boxes) and two sides of each diagonal line.

• Number 1-9 can only appear once in each column.
• Number 1-9 can only appear once in each row.
• Number 1-9 can only appear once in each group.
• Number 1-9 can only appear once on each diagonal line.