As a Criminal your job is to run over pedestrians, mug them, break into their shops and steal their cars; basically, cause as much havoc as possible. As an Enforcer, your job is to stop the Criminals in their tracks. This is what APB is all about.

You'd think, then, that the Criminals and the Enforcers would hate each other. Not just any old hate - the kind that's always overused and applied to everything - but spit in your face if I see you walking in the street hate. There's probably an element of that, but such strong emotion betrays the dependency the two rival factions have on one another. APB's Criminals and Enforcers are intrinsically linked. Without one another, APB would be nothing.

This, I discover during a hands-on session at EA's recent spring showcase, is what's most interesting about Realtime Worlds' Grand Theft Auto MMO, as it's so often been described. Sure, the character customisation, which we've seen at previous events, is incredible, and the game's business model, which allows players to sell user created gubbins to other players for game time, is genuinely interesting. But APB will live or die on the quality of its combat; the simple act of shooting people in the face; the innovative, perhaps even revolutionary way Criminals and Enforcers depend on each other to have fun. As a Criminal, there is no fun in the mindless destruction of AI-controlled flesh and bone, the burning of virtual cars that belong to no-one, or the stealing of cash no-one wants to spend. The fun comes when someone not only cares that you're acting like a tool, but clips you around the ear for it.

I am in the Financial District of San Paro, one of two action districts that'll be live in time for the game's release. I am hanging out of the passenger window of a car, shooting pedestrians in the face for no reason other than I think it's funny. Someone from Dundee, where Realtime Worlds is based, is driving. Another journalist is hanging out of the backseat window, also taking pot shots. We run over lots of people. Lots of them. They scream as they crumble under the force of our metal monstrosity. We are building up notoriety, which, hopefully, will drive the Enforcers crazy.

Our team leader accepts a mission, which then pops up on the top right hand corner of the screen. We are to drive to four cars and burn them. Their locations are clearly visible because APB's objective marker, displayed on the HUD, is brilliant. It only takes a few minutes to get to the first car. I get out, using the classic W,A,S,D control scheme to move, and Shift to sprint, then press F to begin pouring petrol all over the vehicle. Once done, I light the fuel. The car erupts in a blaze of fire. I run back to our getaway car - inside my two companions are waiting patiently. Then we drive off towards the next car.

We can't wait to wind up our defeated opponents by forcing them to hear our composed death themes.

It's not long before an APB - All Points Bulletin - is sent out to Enforcers who are in the vicinity. They will have seen the APB logo flash on their screen, an alert that the game has dynamically matched them as our opponents. There is no lobby. No server to select. No waiting. All this has been done in real time, which, given the name of the developer, is the least you would expect. I am also alerted. I know we are in trouble. The Enforcers are coming.

The engagement begins as a sort of urban vehicle-on-vehicle drive by. I am pumping as much lead from my assault rifle into the enemy car and its passengers as rapid presses of the left mouse button will allow, occasionally zooming in for increased accuracy with a click of the right mouse button. Eventually, our bonnet starts to wave the white flag - smoke is billowing out. "It's going to explode," says my team leader through the game's team-based voice chat. "You'd better get out." I heed his advice.

Weapons are swapped by scrolling the mouse wheel. Ammo is replenished from crates found throughout the city.

On foot, APB feels very much like Grand Theft Auto - that is, like GTA, APB is a third-person shooting game set in a contemporary fictional city. Mouse control makes aiming a breeze, but headshots are difficult. In classic online shooter fashion, most players strafe left and right as they try to keep their targeting reticule aimed, hopefully, at enemy heads. When you do die - and you will, often - you respawn nearby. I spend a lot of time sprinting back to the action. But then, I am an APB virgin.

The Financial District is a twisting, turning, vertical jungle of towering concrete and advertisements. Driving will only get you so far - but it does so quickly. More often than not you'll get as close as possible to your objective marker, then get out and sprint the rest of the way. The F button is used to vault fences, smash open doors, climb up ladders to rooftops and activate all the context sensitive actions in the game, such as pouring petrol on cars. Much of my time is spent climbing and running about, trying to find sneaky routes back to areas I know Enforcers have assaulted. Remember, these are real people you're shooting at. And real people shoot back good and proper.

Occasionally I hear player voices, and they're not from my team mates. That's because APB has what Realtime Worlds calls "locational-based VOIP". If you talk through your headset, nearby players will hear your voice whether they're in your team or not. So, when you scream a profanity after getting killed, be aware that you're doing so in a public space.

In another mission, we're charged with stealing four suitcases full of cash from four separate locations and returning them to a safe point. As in the burning cars mission, we drive toward the objectives in a stolen car. This time, though, I drive. APB's cars seem hard to control at first. The drift-oriented driving model is grounded in reality, but it's clearly been designed to lend the game a dramatic, action feel. It's pretty much essential to use the space bar to handbrake around corners, for example. But you soon get used to it. Driving never gets easy - it always requires careful attention, particularly as a Criminal who's trying to escape pursuing Enforcers - but it's not frustrating. The potential is clear: bumper to bumper car chases and lots of shooting.

Soon enough, an APB is sent out, and a group of Enforcers is hot on our tail. With the suitcases stolen, the mission progresses to a second stage: to defend an area for three minutes. We drive towards the objective and hole up behind cover up on higher ground, waiting for the Enforcers to arrive. When they do, all hell breaks loose. There is a lot of shooting, a lot of dying, a lot of respawning, and more dying. Somewhat inevitably, we fail the mission. The Enforcers have won, and are rewarded with loads of cash. Bah.

You'll be able to sell items you've created on APB's auction house for Realtime Worlds Points, which can in turn be used to buy game time.

What's great about APB, and indeed what sets it apart from most MMOs, is that progression is entirely skill based. Let's be honest, if you put loads of time into most MMOs you'll end up with a powerful character. If you go up against another player who's of a lower level than you, 99 per cent of the time you'll kick his arse, even if you're using your nose to press the hotkeys. In APB, however, your chance to shoot someone in the face is determined by your skill with a mouse, not a dice roll. Really, if you're good at shooters, you'll probably be good at APB. Even though I'd only played the game for half an hour, I felt I had a chance against the schooled beta testing Enforcers. I felt I had a chance not because my gun did 330 more points of damage than my opponent's, but because I know how to headshot.

What this means is that APB is not just another MMO. It's not trying to dethrone World of Warcraft. It's not got orks or elves or flaming swords. It's not, even, a GTA MMO. APB is a massively multiplayer online game of cops and robbers that busts a gut to strip away all the boring stuff you normally find in MMOs. This is why APB has a chance of being something special, and this is why you should care.

APB: All Points Bulletin is scheduled for release on July 2 for PC.