Please use logical thinking instead of guessing! Each puzzle only has one solution.

In pen mode, you can directly import the candidate number by using Shift + number (Alt + number).
In pencil mode, you can directly import numbers by using Shift + number (Alt + number).
Key C (or Del, BackSpace): to deselect the number of the lattice or the candidate number.
Key ESC: to deselect.
Key P: a toggle switch to change from pencil and pen mode.

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.