Just randomly enter numbers according to the rules of the puzzle, but using a blank grid. Start with one or two per 9-square block. To make the puzzle difficult, only enter a few numbers, and add more to make it easier.\n\nIt should be quite simple for a computer program to make a Sudoku puzzle, since there are basic rules to follow. I'm sure the "made by hand" claim is for marketing purposes (though I'm sure it's true).
How do you make a Sudoku puzzle?