The "Sphere of Influence" subtitle refers to the game's focus on the tactical map and how you project power.
: Improving the roads between castles allows your armies to move faster and prevents "bottlenecks" where units get stuck behind each other. Nobunaga’s Ambition: Sphere of Influence Free D...
: Send officers to work on "Work" tasks with neighboring clans to build Trust. This allows you to request reinforcements or secure a marriage alliance. The "Sphere of Influence" subtitle refers to the
: Increases your maximum troop count (population support). Nobunaga’s Ambition: Sphere of Influence Free D...
: Always try to engage an enemy unit from two or more sides. This significantly reduces their morale and increases your damage output.