A squad of four tough-guy soldiers have to take out some foes in a jungle. As the game starts, four soldiers are depicted, with any who are not present to play killed immediately - a joystick adaptor is required for 3 or 4 player games.
Leatherneck resembles Ikari Warriors - waves of soldiers move down the screen shooting at you, and you must shoot them before the bullets make contact. You are armed with grenades to take out mounted turrets, or kill a wide range of enemies at once, but watch out for enemy grenades. There are extra ammunition crates and improved weapons to pick up - waggle the joystick to toggle which one you are using.
Unusually, your shots are long-range and take effect instantly. You cannot change the direction you are facing, instead having the ability to strafe.