Your mission is to rescue hostages held by the enemy. Pilot your helicopter across the border and into enemy territory, to look for the cabins where the hostages are kept. When you find one, blow it open with your machine gun, and then land nearby, so that the hostages can board the copter. Hostages are not invincible, so be careful not to shoot them or land on them while trying to rescue them! Once everyone is aboard, fly back to safety, and drop them off at the post office just across the border. Then you must fly off again, to find the next cabin for another rescue! In the original Choplifter, there are 64 hostages in all, with 16 held in each cabin. Your helicopter happens to be able to hold 16 passengers, so it is possible to rescue the hostages one full cabin at a time. In arcade Choplifter, there are only eight hostages per cabin, and so you can only carry eight at a time.
Of course the enemy is not going to just sit by as you take away their prisoners. Several enemy craft have been launched to stop you. There are jets, capable of shooting missiles when you're in the air, and bombs when you're on the ground. There are tanks, waiting for you to land so they can fire at both you and any nearby hostages. And there are UFOs, curious little ships that will toss bombs when they're not trying to ram you directly! You can dodge these enemies, or engage them with your own machine guns and bombs. If you decide to take them on, remember that your primary objective is still to rescue hostages, and the destruction of your helicopter also means death to anyone you have aboard! In the original game, tanks and jets will not pursue you across the border, so you are safe from them once you have reached the post office. UFOs show no such respect, and in the arcade game, none of the enemies care which side of the fence they're on!
A game of original Choplifter ends when all 64 hostages have either been rescued or killed. In the arcade version, a level ends when you have rescued at least 20 hostages. You then move on to the next level, featuring a whole new setting and a new collection of enemy craft to deal with. If more than 13 hostages are killed in any one level, however, you must start that level over again. Both versions of the game also end if you lose all of your helicopters, so keep a sharp eye on those bad guys and their fire!