Move your mouse across screen (or move you finger across the touch screen, to move your fast-moving, fast-shooting FBI car. Try to avoid bumping into the backs of trucks and other cats, and maneuver your car to slam into the sides of other spy cars to move them off to the side and off the screen to crash.
From time to time, a helicopter will attack you, move the car when it shoots, and move it back when it stop to shoot back at it and destroy it. On the top of the screen you'll see your amount of points on top of the screen, on its right you'll see the speed you are going at (bumping into other cars decreases your speed) and on its left is a pause button.
Make sure to get as many health packs (these increase your health after you bump into other cars. You can find the health bar as a red bar in the upper right corner of the screen). And capture as many flags for points as you continue.