What Bungie has really done with Halo is to take existing concepts and amplify them to extremes. They haven't just designed realistic environments, they've created environments that feel real . The sky isn't just photo-realistic, as you can see from the skimpy screens they've doled out carefully, but it's filled with the most washed out, bright sun you've ever seen. Vehicles are constructed like tiny models, with wheels that run on independent suspensions, and react to the terrain in a unique fashion. Even the rocks thrown up by vehicles are complete with particle physics and colors that are relative to the textures they've come from.
Individual bullets have independent physics, and bounce off of the ground in a spray pattern.
Headlights and flashlights have the same detail as most high-end games nowadays, but have a certain indescribable softness that duplicates the same feeling you get when you stare at headlights in real life. The word in question here, gaming fans, is eerie. There are more vehicles planned for the game, but at this time the only machines in the demo were a jeep, a stealth tank, a hover jet, and a flying alien jet. Planned vehicles for the game include water vehicles, and air combat vehicles of a variety of types. The car obeys real physics, so it's not surprising to see the wheels and body of the car bounce and shake as it takes hills and dirt roads at high speeds.