This is the first release of GNOME Sudoku. The game should be playable and enjoyable at this point, but it is still new software and surely needs a lot of work.
See the INSTALL file for installation instructions (it's not tricky).
There are many sudoku games in the world. For that reason, I've not focused on making this cross-platform -- this is very much a GNOME app. That said, the basic sudoku-solving and generating code works anywhere.
GNOME Sudoku takes care to generate valid sudoku -- symmetrical puzzles for which there is a unique solution. If it generates a puzzle that is not unique, this is a bug.
See the FAQ for some more information on sudoku itself and the game.