Just as it says. You play a guy who goes around stealing cars and other vehicles (planes, trains, boats, and more!). Driving them through towns (and buildings!), motorways, and cross country.
Alternatively you can play as the cop after the joyrider. Just like COPS.
All in an effort to collect  the best cars and money (from selling the cars) to leave and go onto another part of the world, or to book all the joyriders in the city before being transferred to another city in another part of the world.
You can collect weapons for your character and your vehicle.
There is also a two player split-screen/link mode, much like Twisted Metal combined with Need For Speed.