Sudoku Dream is a great sudoku game in which the objective is to fill the empty spaces with numbers in a way that each column and row (horizontally and vertically) has all the numbers from according to the size you've chosen. The program offers multiple sudoku sizes (tiny, small, medium, large and huge) and different difficulty levels (very easy, easy, medium, hard and very hard). According to the size and difficulty level you've chosen the game will be more or less challenging. What is more, the program allows you to enter the numbers by hand, so you can play sudokus you've seen in magazines or newspapers and solve them. All the puzzles can be saved in case you want to continue them later or printed to take them wherever you go. In addition to this, the program comes with an assistant that can show mistakes, show a random or a desired cell in case you get stuck, show a markup, show solution, and do a scan to check your solution.
In short, Sudoku Dream offers all you may need to play a good sudoku game and the best of it all is that it is completely free.