Anachronox, by Ion Storm

Anachronox is a 3rd person, 3D role-playing game (RPG) using the heavily-modified Quake 2 engine (32-bit graphics, particle system, spline-based camera scriptor, APE programming language). The player controls up to three characters at a time, from an eventual cast of seven, exploring the galaxy. Gameplay is exploration and interaction of the environment, melee with various galactic foes, and discovery of unique weapons and items that aid you on your quest. You can choose different characters to play and different ways to do things, leading you to different events and areas in the game. Each character has different Battle Skills with unique effects, and World Skills they can use to access places and info the other characters can't.