World at War will use Call of Duty 4's engine with some tweaks. The physics are improved and environments more destructible. Explosions will take out buildings and fire engulfs trees and houses alike. Bullets can slice through wood to create new paths or just to attack an enemy in hiding.
Call of Duty 3 was nothing short of a debacle, but given that the Treyarch development team only had a window of eleven months it is surprising the game turned out as well as it did. With a two year development time this time around, Treyarch's doesn't have any excuses. To that effect they are taking out all the stops, like enlisting the talents of Kiefer Sutherland and Gary Oldman to do some of the key voice acting.