Best XBox game?  

Please share what is your favourite XBox game...
My personally favorite is Ninja Gaiden Black. Ninja Gaiden for the Xbox didn't leave a lot of room for improvement, thanks to its astonishingly good presentation and fantastic action, which combined the depth and precision of a great fighting game with the settings and situations of a first-rate action adventure game.
But this new installment seems bent on achieving nothing less than perfection by using last game as a starting point and fine-tuning its few issues, while also adding lots of new options and content, such as a lengthy series of stand-alone missions that emphasize the game's unbelievably intense, brutal, lighting-fast combat.