Sudoku grids in Puzzles update automatically every day, providing a new challenge each time. Each difficulty level has one solution from the previous day, stored in Solutions. Grids are generated with Python and displayed in the browser using Brython. Currently, printing multiple grids for offline play isn't available yet, but this feature is being considered for future updates.
A reminder of the rules:
One of each number in all 9 vertical lines.
One of each number in all 9 horizontal lines.
One of each number in all 9 squares.