When it comes to keeping secrets, the games industry is about as trustworthy as Julian Assange. Just ask Konami, whose VGAs-closing trailer revealing MGS: Rising as a Platinum Games title leaked online hours before the show.

And yet, defying the odds, news of two-years-in-the-making The Last of Us, created by an 80-strong Naughty Dog team no-one knew existed, was met with that rarest of emotions when it broke cover at the weekend: genuine surprise. But, oh, how close it all came to unravelling as the big day approached.

Two months ago, Neil Druckmann, creative director and writer on the project, left his iPad on a plane. An iPad with the debut trailer for the game stored on it. Frantic calls to the airline ensued, but the device was gone. Naughty Dog waited nervously. And, to its considerable relief, nothing happened.

Druckmann and game director Bruce Straley began work on The Last of Us after completing Uncharted 2. No-one outside the company realised this, until a friend of Druckmann's noticed his name wasn't in the credits for Uncharted 3. But, once again, he managed to shake off suspicion.

Then, one week before the VGAs, studio co-president Evan Wells emailed the entire company warning everyone not to bugger everything up with a careless whisper on Twitter or Facebook. "Don't be that guy."

With days to go, a teaser site named the game, but there was nothing to link it to the studio. Or so everyone thought. A clue was uncovered in Uncharted 3 and word quickly spread across the internet. But, in spite of the evidence, Naughty Dog's involvement was dismissed since, as everyone knew, it was a "one game studio".

The team has tweaked Uncharted 3's tech to allow for more detailed facial animations so the characters convey a greater range of emotions.

"We were very serious about keeping it a secret, limiting the people that we're exposed to it even internally in Sony," admits Wells. "It never crossed our mind that putting an easter egg like that in Uncharted 3 would rat us out."

It turns out that this easter egg was included before the game's original planned announcement at E3 2011. When that changed, Naughty Dog forgot all about it. Luckily, though, it wasn't until the company's logo faded into view on the big screen on Saturday evening, that the penny finally dropped. What a carry on.

The trailer itself has been the subject of intense debate since it aired, largely because it raises more questions than answers. Or maybe that's because we're not looking hard enough.

"If you break down the trailer, all the action there is meaningful," says Straley. "It's teasing the different kind of mechanics you're going to be playing with in the gameplay set-ups. There's some melee and a gun - where that goes as a strategy is kind of intriguing."

So what do we actually know about The Last of Us? It's a third-person action-adventure with survival elements, set in a post-apocalyptic world after most of the population has been wiped out by a deadly virus, while those remaining are threatened by infected, zombie-like humans.

The Last of Us main theme in full:

The inspiration for this was a gruesome sequence from the BBC's Planet Earth series, featuring Cordyceps, fungi that invade and kill insects. The starting point for the game, then, was the question: "What would happen if it jumped to humans?"

Locations will all be US-based, moving around the country from city-to-city.

Major artistic inspirations, meanwhile, include the movies No Country For Old Men and The Road, comic The Walking Dead and WWII novel City of Thieves.

Contrary to evidence in the trailer, however, The Last of Us is "not a zombie game," insists Straley. Druckmann explains: "If the game was about the monsters, we would have not showed them. The story's not about them, so [we thought] let's get it out of the way."

Instead, he wants us to consider the relationship between its two lead characters. Joel is a survivor and anti-hero (played by Troy Baker), and Ellie is a 14 year-old girl (played by 28 year-old Ashley Johnson) with no memory of the world pre-apocalypse.

"What are those non-verbal signs [in the trailer] saying about how long they've known each other. What about the other non-infected person?"

The game will play out across various US cities and it's suggested that survival will involve both killing and scavenging. Do you control Joel alone? Ellie? Both? Is it co-op? Naughty Dog isn't saying.

"It's story-driven, [but] the whole triangle is story, gameplay and art," says Straley. "As a gamer it's all about strategy and giving the player enough tools in their toolkit so that they can come upon something and choose and have the consequences play out within their choices."

If the movie True Grit can have a strong 14 year-old girl in a lead role, asks Naughty Dog, why not a video game?

How those choices play out remains unclear, but don't expect any kind of Heavy Rain-esque branching narrative. "We're telling it the way we've been developing this method at Naughty Dog," explains Druckmann. "We're evolving it, but I can't say anymore."

And that's because he'd rather talk about story. And not just any old story, but one Druckmann wants to "change the f***ing industry" with - "because we feel like storytelling is so poor right now". Aside from the all too few likes of Valve, Irrational and Rockstar, it's hard to disagree.

He continues: "We try so hard at Naughty Dog to push things and then games come out that are fun and exciting and get visceral things right, but to read in reviews that they have an amazing story is disheartening to us because we work so hard at it."

Take the majority of games with a post-apocalyptic setting. "In any other medium it's all about the characters. [We want you to] care so when horrible things happen you feel something. That's what Naughty Dog can bring to the genre and really own it: every decision we make is about the characters and their relationship".

That explains the choice of composer, two-time Oscar winner Gustavo Santaolalla, whose credits include Brokeback Mountain and Babel. "With this music we're trying to get emotion - we're not going for horror," says Druckmann.

"We approached this genre because we felt no-one is getting to the heart of it. [The Last of Us] tells you something about the human condition - that's what you want to do as a storyteller."

With that in mind, imagine the shockwaves that reverberated around the Naughty Dog office when they saw that Dead Island trailer.

"We saw it and we thought, wait a minute, someone else is doing this - it's really moving, there's this family that's been torn apart," says Druckmann. But, as we now know, it bore little relation to the finished article.

"You saw the game and it wasn't that," he adds. "I'm not saying whether it was a good or bad game, but it wasn't that. And we feel our trailer is very representative of what we're going for." Not least because the footage is all in-engine.

With a bloody corpse, a brutal murder, a bullet to the face and a knife to the back of an infected human in the trailer alone, The Last of Us is set to be Naughty Dog's most violent game yet. But Druckmann insists it will not be "gratuitous - the monsters are not the focus. It's the relationship between Joel and Ellie."

So if not a horror game, what is it? "This is going to sound corny and it might not appeal to gamers, but I would say it's a love story," he says. "It's not a romantic love story, it's a love story about a father-daughter-like relationship."

This was in part influenced by the memorable sequence between Nathan Drake and Tenzin, his Tibetan guide, in Uncharted 2. "We kept joking, wouldn't it be intriguing to develop a whole game where you're building this relationship, not just a level," he says.

An even greater influence was the birth, 18 months ago, of Druckmann's first child. This had a profound effect on the direction of the story - in fact, he reveals that the name Ellie was actually one originally considered for his daughter, chosen for the game to make it more personal to him.

"What does it mean for a teen to grow up in this world? If you see bleakness everywhere, how do you be a kid in this world?"

The team's passion for and belief in the project is palpable. Having made one of the outstanding games of this console generation, it would have been natural to expect Druckmann and Straley to dive straight into Uncharted 3. But they wanted to do something different, and so, for the first time, Naughty Dog became a two-team studio.

"Over the years we've staffed up an incredible team - these people at any other studio could be leads," says studio boss Evan Wells. "When you have a franchise like Uncharted you become a target for headhunters and recruiters - basically everybody in the company's been asked if they'd like to come some place else.

"We were afraid that if we didn't give these people the opportunity and the responsibility to try something different in their career, one day one of those calls might stick. So really we just wanted to embrace the talent we have here and give it a shot."

When the fruits of this labour of love will be shared with gamers, no-one is saying. And, in the wake of the brutal crunch endured by the Uncharted 3 team in order to meet a release date it recklessly announced a year in advance, that should come as no surprise.

"We will never do that again, not a year out," sighs co-president Christophe Balestra. Wells agrees: "The minute we saw [the date] on screen we were like, oh god, I really regret that."

So, while the game has already been in development for two years, with the team not yet ready even to discuss gameplay let alone show it, don't be surprised if The Last of Us fails to materialise before 2013. It'll be done when it's done, as the saying goes.

In the meantime, those of us desperate to see where Naughty Dog can take the medium next - and how wonderful it is to see such a talented, successful studio remain so eager to push boundaries rather than settle for the same-old - will have to tolerate the agonising drip-drip-drip of information.

Take the "no network play" note on the official PlayStation website. "We don't know where that came from," says Druckmann. "That's TBD," says Straley.

Best keep an eye on your iPads, chaps.