There's
a Hearts of Iron II Q&A on HappyPuppy talks with Fredrik Lindgren of Paradox
Entertainment about their World War II RTS sequel: "We wanted to make the combat
system more realistic and better reflect the grand strategy scale of combat. By
introducing the 'movement-is-attack' system, combat is started as soon as troops
move into a province, making it hard for the enemy to foresee a planned attack.
The mission-system for units makes it possible to give detailed orders and
decide the level of unit control."