Operation Hanoi is a one player game where the action is viewed as a 1st person perspective as the game scrolls to the right. Enemy soldiers and vehicles appear from the sides and top of the screen. You control crosshairs on the screen to aim and fire; grenades can also be thrown.
You only have so much ammo so shoot parachutes falling from the sky which carry extra ammo as well as 1st aid boxes to keep you alive. As well as your main playing area you can also see your score, ammo, lives, amount of enemy and a hits bar.