Description taken from PlayStation 2 version of this game

In the cockpit of 16 different modern planes is where you spend most of your time in Heatseeker. Playing as a member of an international task force, you must work your way through 18 missions by taking out enemies on land, in the air, and at sea. Often during a level you will receive additional objectives to be completed for bonus points. Three difficulty levels and the ability to switch between realistic and arcade controls let you adjust how seriously you take your game. Each successfully completed mission unlocks upgrade options for the weaponry of your plane. There are over 40 bomb and missile improvements, however most of them can be equipped only on specific jets. ~ Gracie Leach, All Game Guide