I have a few requests:
(a) Provide a way to set my own background images for sleep and turned-off modes.
(b) Display the owner's name and other information such as phone number in the main menu
or while in sleep or turned-off mode
(c) The current sudoku game is lost when returning to the main menu. Please save its state.
(d) In soduko, it is very easy to fill a square by mistake. I propose to automatically deselect the current number (in the bottom left area) after filing a square.
It should be noted that (b) could be solved by (a) with an image showing the user coordinates.