At A Glance:

- Free approach to off-mission objectives

- Reputation meter affects how the world responds to you

- Invasion multiplayer mechanic enables players to enter other games and hack players

VideoGamer has just seen two demos of Watch Dogs, with one being behind-closed doors. The first was the demo from the Sony conference, where Aiden has to rescue affiliate T-Bone, who has been traced and is hiding out in an apartment. Aiden uses various abilities to do so, opening access gates and hacking surveilance cameras - at one point a pedestrian attempts to call the police before Aiden grabs his phone and smashes it (one of many ways you can neutralise people who have recognised you).

As before this demo ended with T-Bone escaping his would-be assassins - with the help of a hacked soundsystem and moving advertising hoardings covering his escape. Again, Ubi showed off its asymmetrical tablet integration, with one of the level designers raising bollards to stop incoming squad cars before Aiden escapes and the demo ends.

The second demo was described as a 'systemic'. The first was linear, this one was about exploring the open world. Aiden is shown in a district called the Wards, a poor Chicago district. It's an imposing place, and Aiden can't hack the populace as he hasn't unlocked the district yet - Ubi's way of controlling progression. The place itself is run-down, autumnal, a rusting brown slice of industrial waste, slanted and flimsy corrugated iron gates giving him infiltration opportunities.

After hacking Blume Corp's ctOS server - and encountering the company's heavy handed guards, he profiles the security goons, finding out some interesting details: one fishes with dynamite. Hacking the superior officer gives Aiden the codes to enter the building, at which point players can take what Ubi describes as a free approach to infiltration - stealth, hacking, all-out killing: or a combination of all of them.

Inside, Aiden hacks a forklift as a distraction before killing the approaching guard with an IED. Things went pretty Rambo from there on out, as assault rifle fire rings out more than the word 'lad' at a local pub. Using Focus mode, he takes out his foes easily.

After hacking the building, Aiden now has opened the rest of the area up, in a similar way to Far Cry 3's masts or Ass Creed's vantage points.

A Minority Report-style crime prediction system gives you the edge on the word: Aiden follows an NPC marked by ctOS as a potential crime victim, running into her assailant before getting into a foot and automobile race through a factory district. Raising bollards kills the speeding offender, increasing Aiden's rep - perception is a big thing in Watch Dogs, and it can rise or fall depending on whether you're seen doing good or bad deeds. It's all a degree of shades of grey however, as killing bad guys won't always increase your rep.

Another district, the Loop, shows off Watch Dog's economy - buying and selling guns, selling items you've found, constructing weapons. The Loop is a historical district, and one that is affluent, affording Aiden the opportunity to nick a sports car and speed through downtown to lose the cops.

By hacking successive wifi points, Aiden then hacks the apartment of a random NPC, going in through a webcam and stealing credit card details to draw out money at a later date.

Aiden isn't the only one who can hack - he gets hacked in the demo, and has to use the ctOS profiler to positively ID the target. Again, you can do that on street level or hack a camera for overwatch. The best part is that the hacker was another player, who had invaded the game Dark Souls-style.

If they get away, as they did, you can respond by invading their game. Players won't know until they're hacked or attacked themselves, leading to some interesting games of cat and mouse; hiding in cars, rooftop chases, full-blown gunfights down busy streets. It's another great feature in a game that could be one of the best of the year.