Spy Hunter is an action/driving game. It places the player as the driver of a G-6155 CIA Prototype Interceptor sports car. The object of the game is to travel the freeways and waterways, hunting down and destroying as many enemy vehicles as possible, all the while not harming civilian vehicles. The view is top-down and the screen scrolls vertically underneath the player's car.

The game begins with the player driving the G-6155. Soon, the player starts to encounter enemy vehicles which try to force the player's car off the road and crash. Each enemy vehicle has its own special feature, such as tire slashers or bulletproof armor.

Points are scored for driving on the road and for destroying enemy vehicles. There is a lead-in time when the player has an endless supply of cars. After this time expires, the player will lose a life each time the car crashes. Extra cars can be earned with high scores. The first extra car is earned at a default value of 30000 points, but this value can vary depending on settings.

The player must be careful to avoid harming civilian vehicles on the road. There are three types: blue automobiles, pink automobiles, and motorcycles. Hurting these vehicles causes scoring to stop briefly, during which time the player’s score reads 'NO POINTS'.

Initially, the only weapon the player's car has available is a dual front-mounted machine gun which has an endless supply of ammunition. Early on, these guns and the player's driving skill are his only weapons against the enemy cars. The player can also attempt to force or ram the enemy cars off the road. Eventually the player encounters an ally, the weapons van. After the player drives past the weapons van parked on the side of the road, the van accelerates past the player's car and positions itself in front of it and drops a ramp. The player can then drive up the ramp to enter the back of the van. The van then pulls to the side of the road and deploys the spy car equipped with a new weapon. A symbol atop the weapons van indicates which type of special weapon it carries. The player is not obligated to use the weapons supplied by the van. Also, if uninterested, the player can simply ignore the van and drive past it.

There are three special weapons in all and they can all be equipped simultaneously. The special weapons consist of an oil slick, a smoke screen and missiles. Each special weapon has a limited number of uses. The smoke screen and missiles can each be used three times. The special weapons are activated via dedicated buttons on the steering wheel. Once the weapons ammo is depleted or before, the car can be refitted with a new supply from the weapons van.

There are six enemies in all, each with their own special characteristic :
* 'Switchblade' or 'Never To Be Trusted' cars have tire slashers. Knives pop out of this car's tires and can force the player's car to crash if they touch his tires.
* 'The Road Lord' or 'Bulletproof Bully' cars have bulletproof armor plating; machine guns are ineffective against these cars.
* 'The Enforcer' or 'Double Barrel Action' is a limousine with a shotgun toting thug who shoots at the player's car.
* 'The Mad Bomber' or 'Master Of The Sky' is a helicopter which drops bombs. This enemy can only be destroyed with missiles.
* 'Barrel Dumper' is a boat which drops lethal explosives into the water.
* 'Doctor Torpedo' is a boat which shoots torpedoes at the player's ship.

Occasionally a message appears on screen that says 'Bridge out – Detour on Left'. Then the player must drive his car into a boat house located alongside the road, otherwise he will crash into the water and lose a life. After driving through this house, the player’s car is turned into a speedboat on a river, with enemy boats which try to destroy the player. In this area, if the player uses the oil slick, the boat instead issues a line of fire which destroys any ship directly behind the player. In this area, occasionally the river splits; the left side continues the river, the right side causes the player to drive through another house where the boat is changed back into the car.

Later in the game the player gets a warning that there are 'Icy Roads Ahead', then the player enters an area that has white road which is very slick. The icy roads section eventually ends and goes back to normal roads. Icy roads occur again on and off during the rest of the game.