Watch Dogs preview: hacking Big Brother in connected, crime-ridden Chicago

It's that old superhero dilemma: if you see a crime, is it your responsibility to stop it? What if you think the victim deserves it? Watch Dogs ' protagonist has a lot in common with Spider-Man – he's just a bit more OK with murdering. Well, a lot more.

Chicago is run by CtOS, a network of computers that manage the city's services, including traffic lights, trains and security cameras. With his phone, Pearce can control these systems with a single button, and can also tap into other phones to steal private information. He's not above emptying an innocent's bank account in pursuit of vigilante justice.

Pearce protects the people at the expense of their privacy. In his tools is the city's crime prediction algorithm, which digs through personal information to spot potential victims before they're attacked. He doesn't have to intervene in crimes he witnesses, though. In the live demonstration I saw, Pearce stayed hidden while a suspected rapist was murdered in an alley. Geez.

The fidelity of the alley and characters made that scene feel especially gruesome. The world looks properly lived in – not as sterile as GTA 's satirical cities – with grubbier neighbourhoods speckled with graffiti and litter. Litter that, thanks to Ubisoft's new Disrupt engine, realistically flutters around in simulated wind.

When Pearce walks into a pawn shop, the light is snuffed out and street sounds give way to thumpy beats and the whine of fluorescent lights. The people in and around it walk with purpose and loiter with intentional lack of purpose. They aren't just NPCs there to scream and be run over – they have stories and personalities.

Or, at least, Ubi create the illusion that they have those things. Personal details about pedestrians pulled up by Aiden's augmented reality HUD reveal hobbies, fears, shortcomings and fetish porn – a snippet of a life as a catalyst for our imaginations. It's an effective way to convince me that I'm looking at a city full of real people, but I can't shake the feeling that I'm watching an elaborate stage play, no matter how good the motion-captured animations are.

Watch Dogs approaches the uncanny valley of open worlds; it's close enough to convincing that it induces Truman Show- like paranoia. Given the theme of the game, that unease may be an asset.

When not quietly admiring the city's fidelity, Aiden keeps busy by starring in a violent action game. Actually, I'm told that Watch Dogs can be played non-violently, but what I saw was Pearce slowing down time with Focus mode (hey, Max Payne can do it, so whatever) and shooting people's faces. In his defence he prefers to murder bad guys where possible, but if a stray bullet hits someone... well, that's more manslaughter, isn't it?

Aiden's first conflict in the demo starts off with friendly, non-lethal takedowns, the player using his hack-o-matic to turn on a forklift and open a gate, distracting nearby guards so they can be sneaked up on. Hacking is all binary decisions – turning something on or off, or assuming the POV of a security cam. Interestingly (and nonsensically), cameras can be chained together, because hacking only requires line of sight. This is how Aiden eventually infects a CtOS server with a virus without ever entering the building.

But first, it takes a cover-to-cover firefight to finish off the guards outside. Despite his usual slow pace Aiden shows bursts of athleticism, traversing the lot with daring parkour leaps and using Focus to chain deadeye shots. Focus mode and quick-draw hacking look to be especially important when driving, during which Pearce can change traffic lights and raise concrete blockers to end the careers of the cops in pursuit with spectacular crashes, the camera swinging around for slow-mo Burnout -style views of the wrecks. Sure, the world stops feeling quite so grounded and natural here, but it does look fun.

Like in GTA , a five-point gauge indicates the level of police engagement, and he must break line of sight to escape. In one version of the demo – which Ubisoft provided as a video – the driver hacks open a parking garage door, glides into a parking space and strolls away like he's reenacting the opening scene of Drive. If nothing else, I want to do that

Tyler grew up in Silicon Valley during the '80s and '90s, playing games like Zork and Arkanoid on early PCs. He was later captivated by Myst, SimCity, Civilization, Command & Conquer, all the shooters they call "boomer shooters" now, and PS1 classic Bushido Blade (that's right: he had Bleem!). Tyler joined PC Gamer in 2011, and today he's focused on the site's news coverage. His hobbies include amateur boxing and adding to his 1,200-plus hours in Rocket League.