Stuart Hatch can supply Sudoku puzzles for your Website. Besides the traditional "numbers game", I offer puzzles that use letters instead of numbers and the shaded squares contain a "secret message". In these examples, the message is a phrase taken from the gospel indicated.
The puzzle is solved on the Webpage (no downloading or printing necessary), and I supply the necessary software and files. You do not need to have an StuartHatch.net Website. The cost is £15 (US$30) for the software and the four puzzles in the demonstration. Additional puzzles are available at £2 (US$4) each. I can even produce a puzzle with your own "secret message" for £5 (US$10).
The grid displays the permissible letters in each cell in small, grey text. These letters are removed by clicking on them, and clicking on the last one remaining after eliminating the rest selects that letter as the solution for that cell. Alternatively, click on the cell and enter the letter from the keyboard. This facility can be turned off by clicking the "Assist" button. Click "Help" for a full explanation.