Splinter Cell. It looked amazing and completely set the standard for how 3D action/stealth should play, imo.

Metal Gear Solid 2

Knights Of The Old Republic.

if we count multiplats: Silent Hill 2, if not: Panzer Dragoon Orta

Star Wars: Knights of the Old Republic.

Because it's Knights of the Old Republic and Knights of the Old Republic is one of the best games ever made. To me almost the best game ever made even, bested only by one other game. The game's basically perfect, from it's gameplay mechanics to it's cool characters to it's 'Star Warsy-story' (with the biggest plot-twist ever) that's more 'Star Wars' than actual 'Star Wars' movies. It's so good it's the only game I ever payed money for to get it on mobile.

KOTOR. Man, I really need to play it again. Such a masterpiece.

Since I'm always happy to shine a light on an under-appreciated console, I want to nominate a few others.

Far Cry Instincts - an enhanced port of Far Cry with great combat and exploration
Doom 3 - a tense and scary shooter dripping with atmosphere
Ninja Gaiden - an all-time great hack-n-slash that's brutally difficult
Fable/The Lost Chapters - a quirky and unique action RPG
KOTOR - one of the best and most engrossing RPGs of all time
Splinter Cell - a gorgeous-looking, slow-burning stealth game
Psychonauts - the best 3D platforming not made by Rare/Nintendo
Morrowind - an open-world RPG for the ages
Halo 2 - this sequel boasts a great campaign and multiplayer mode
Half-Life 2 - a one-of-a-kind adventure with amazing physics
Jade Empire - a deep combat and morality system make this game shine
Republic Commando - a satisfying squad-based shooter with personality
Freedom Fighters - an overlooked gem of a tactical shooter

Man, Xbox had some great games :)

Kung Fu Chaos! Best fighter on the system and you could install your own music.... great times!

Surprised to see so few votes for Half-life 2, considering how beloved that game is.

Ninja Gaiden Black