To create a custom Sudoku puzzle, first create a Sudoku solution. Then remove some of the answers in a symmetrical fashion. Finally, check to make sure there is a single solution to the puzzle.
- Build a Sudoku solution
Fill out a grid with a solution obeying all Sudoku rules. Typically, this follows a grid that is nine rows by nine columns. Then break the grid down into nine three-by-three sections. Make sure that each number is used only once in each row, column and three-by-three section.
- Erase some of the answers
Remove answers from the completed solution. Typically, this is done in a mirror pattern to maintain symmetry. You can remove just a few for an easier puzzle or many for a more difficult challenge.
- Make sure there is only one solution to the puzzle
For the puzzle to work, there should only be one possible solution. This can be done manually but can also be done with software such as Sudoku Dragon. When you ask for a hint for his puzzle, this software returns an error message if there is more than one possible solution. If such an error appears, then you may need to begin the process again.