Sly Cooper & the Theivius Racoonus is the first game in the Sly Cooper series. It featured a 3D world, different missions that you must complete to move on to the boss, and more. What makes this game so good is probably the level of sneaking around and the variety of missions.
The graphics of this game are... Ok. Somewhat cartoony. But it needs to be cartoony for a game about talking animals that stars a raccoon (Did I mention it was about a raccoon? Yup. It is). But don't let the graphics fool you; every respectable Playstation 2 junkie should own this game.
I'm going, I'm going!