In contrast to most simulators of the era, Harrier Assault puts the user in control of the overall battle, assigning missions to both air and ground forces.

The game is set in a fictional conflict between United States forces and the Indonesian army occupying East Timor.

The carrier group is equipped with a squadron of 16 AV-8B Harrier II jets, a number of CH-46 Sea Knight and CH-53 Sea Stallion helicopters stationed on Tarawa and the escort vessels and a brigade of AAV-7A1 Amphibious Assault Vehicles, tanks and support vehicles aiding the marines and the special forces units.

Players can completely ignore one of the elements and either play a pure real-time strategy game controlling the forces as the battle plan progresses, or alternatively participate only in combat, flying the AV-8B Harrier missions.

Similarly, flying some missions is essential, e.g. intercepting C-130 planes carrying enemy reinforcements, something that the game's AI cannot handle.

Inside the cockpit, the HUD and MFD provide combat information of enemy units along with aircraft and mission data and the point of view can be rotated left, right and back.

The editors wrote, "The success of Domark's definitive Harrier flight sim hung on the depth and complexity of its enormous campaign".