Sudoku can build easy and hard Sudoku puzzles. It can also solve any Sudoku puzzle at once or step by step. The engine of Sudoku is a Knuth's algorithm, Dancing Links, that may be used to solve many problems besides Sudoku. So, I've inserted it in the Util subsystem. You found an exe file ready for running at http://gemeu.free.fr/Sudoku.exe for the French version, and http://gemeu.free.fr/en/Sudoku.exe for the English one.