If you are a fan of solving Sudokus, then don't miss out on Just Sudoku, in which there are five difficulty levels and hundreds of games, with instant on-line solutions.
In this game you will find loads of free Sudokus. You can solve them as they are offered on-line, or print them out, or even export them to PDF format.
The rules to solve a Sudoku are simple: in each column, in each row and each box of 3x3 you need to put the numbers from 1 to 9 just once ... these are the instructions for Sudoku. So simple, yet so addictive.