The Orange Box - PC Characters - Advanced facial animation system delivers the most sophisticated in-game characters ever seen. With 40 distinct facial muscles, human characters convey the full array of human emotion, and respond to the player with fluidity and intelligence Physics - From pebbles to water to 2-ton trucks respond as expected, as they obey the laws of mass, friction, gravity, and buoyancy Graphics - Source's shader-based renderer, like the one used at Pixar to create movies such as Toy Story and Monster's, Inc., creates the most beautiful and realistic environments ever seen in a video game. AI - Neither friends nor enemies charge blindly into the fray. They can assess threats, navigate tricky terrain, and fashion weapons from whatever is at hand