Warning: If you haven't played Deus Ex, but have maybe bought it in a Steam Sale as something you're absolutely going to play one day, this article will drive a twelve-car train of spoilers through that dream like you're Leonardo DiCaprio in Inception.

A piece of driftwood internet wisdom that sometimes floats past on gaming messageboards goes something like this: every time you mention Deus Ex, someone will reinstall it. Somewhere, wheezing for breath under the clutter of my room/workspace/habitat, is my original Deus Ex CD-ROM, which I bought aged 12 on a whim with pocket money.

My reasoning was solid: I'd never heard of the game, but the back of the box promised guns and conspiracies, and the dude on the front was rocking some dangerously cool shades. Little Me might not have known much about global banking conspiracies or the Trilateral Commission, but you could coax him onto the cyberpunk neo-anarchist bandwagon with a pair of polarised Wayfarers and a trench coat.

Fourteen years later, I've lost my fake RayBans and even the local Brixton drug dealers don't wear trench coats. Sunglasses at night went out with Corey Hart (or at least with Keanu Reeves). Deus Ex did indeed have guns, but even at the time they were inexcusably horrible to use. The game's not even a looker anymore – more a kind of papercraft tribute to how you think you remember it looked, with weirder walking animations.

So why do I go back to it? Because leaving aside its wackier conspiracy theories, it's the quality – the prescience – of Deus Ex's story that makes it such a great game to play in 2014 – in a horrible, unsettling sort of way. Revisit the game today and nano-augmented super-agent JC Denton's quest to unravel a global conspiracy doesn't seem twee or outdated. Somehow, it seems timely: moment after moment of sneering, political philosophising about money, health, corporations and the poor, punctuated by regular, 400-volt jolts of "wait, when was this written?"

Unlike the most recent instalment in the franchise – 2011's (great) Deus Ex: Human Revolution – the original Deus Ex doesn't drag you by the wrist right to the centre of its narrative. You aren't the bodyguard/confidant of a global leader in the human augmentation industry and your girlfriend isn't the brilliant, one-in-a-million scientist whose research holds the keys to the future of humanity's advancement. In DX1, you are, basically, a thug. A genetically engineered, laser-precise piece of next-gen thuggery, it's true – but a punchy cog in the wheel of big government nonetheless. Go here. Do that. Shoot them. Video game protagonist 101.

The set-up at the game's start deliberately plays on the unimpeachable FPS hero trope. Only if you slow down to read the game's scattered newspapers, public information terminals and hacked email accounts do you find out how rotten the world of Deus Ex really is, and that apple only decays further the deeper you burrow.

Your first mission ends with an interrogation with a captured terrorist leader. His group have stolen a shipment of vaccine (called Ambrosia) for a plague that's decimating all but the wealthiest in society (who can afford the cure). Your sole objective is to find out where the terrorists are taking it, so you can nab it back.

"Well done!" Your handler beams over your brain implant, once you do. "Report back to base. Mission complete."

But if you stay on after getting your answer, you can press the leader on his motives. What you get for your trouble could be an opinion column from a 2014 Sunday newspaper. This guy, who until 30 seconds ago was the target of an anti-terror raid (and who you can just waste in the head, if you feel like it, to the chagrin of your superiors), is suddenly flitting between Occupy movement rhetoric ("Ever wonder by the big car companies pay 2 per cent tax, while the guys on the assembly line pay 40 per cent?") and pro-Wikileaks soundbites ("Did you ever ask what it's for? The surveillance? The police? Is that freedom?"). Besides the boxy, 4:3 ratio TVs back at counter-terrorist HQ, there's not a thing in the thematic nature of DX1's opening mission that's aged a day.

"Regarding the 99 per cent [question], it's funny," says Deus Ex's lead writer, Sheldon Pacotti. "I guess I've always had a populist streak in me. I can't speak for the rest of the development team, but even before the economic shocks of the 2000s I was preoccupied with the smallness of individual people compared to modern companies and governments. It's hard to own your own career – and identity – when you often don't even see the faces of the people deciding whether or not your job exists. You're even more alienated when the 'decisions' are really just the result of impenetrably complex macro-economic processes. This vastness of scale is a direct outgrowth of technology".

The game's first big twist is that the National Secessionist Force (or NSF), which you've been bravely gun-plugging in the name of maintaining order, are actually the good guys: regular people pushed into fighting for their lives and livelihoods and then conveniently branded 'terrorists' by their government. The world that they live in is leaving them behind, as the rich pull away from the poor and employ people like you to police the divide.

As JC, you see both sides of the equation in the way that no other in-game characters do: the elite live in fancy apartments and mansions (which you break into and pillage for goodies), while New York is filled with the sick and the homeless - either living in crappy rented rooms in the dilapidated 'Ton Hotel, or in ragtag communities in abandoned subway stations. Deus Ex's augmentations (the biomechanical enhancements that give JC and other UNATCO agents their awesome, murderous powers (and the series' signature mechanics)) are huge technological advances. But the more you explore, the more you realise you're one of the chosen few who can enjoy them. These frightened, desperate people are being stacked against a Terminator. As the defenceless NSF leader puts it before he's carried off, never to be seen again: "Who's the scary one, huh? Me or you?"

One famous piece of trivia about Deus Ex is that, if you look at the city skyline during the missions set in New York City, the Twin Towers are conspicuously absent. The real reason for their exclusion isn't very interesting: something to do with memory constraints. So in the game's fiction, the Towers were destroyed by terrorists. Deus Ex was released in 2000, a year before 9/11.

But the game makes a more direct prediction about terrorism in the 21st Century in its first level, in which (before interrogating the NSF leader) JC is tasked with turfing the NSF out of the Statue of Liberty. The statue itself was destroyed previously in the game's fiction, losing its head and its torch. But the group responsible are domestic terrorists, and the attack therefore a symbolic one: in Deus Ex's world, the American people feel they're now subjects of a wealthy and corrupt elite working against the interests of the common man. Politicians and their families get plague vaccine while their own loved ones die in gutters. 'Liberty' is just a statue.

"I think the game's most accurate prediction comes in how terrorism operates in the story", says Pacotti. "From the mission ideas to the way characters strategise and explain themselves, the game dramatises the idea that 21st century war will be waged with symbolic acts. Before September 11th, though terrorism was prominent in the news, the notion that terrorists would destroy a major landmark like the Statue of Liberty seemed far-fetched, but now it's clear that modern wars are TV shows where both sides compete to write the script. PR has always been a part of war, but 24-hour news and the internet has made it almost the primary battlefield."

The responses of the powers-that-be to the threat of terrorism in the first Deus Ex are also eerily prescient, especially in their dehumanisation of the enemy. For the first chunk of the game, JC works as an agent for the United Nations Anti-Terrorist Coalition (UNATCO). Although you can choose to play a stealthy, non-lethal character, if you go soft on UNATCO's enemies, the veteran field agents will chew you out and question whether you've really got the stones for the job.

"The terrorists have wired the platform with explosives and put in hostages", says your sometime-mentor, Anna Navarre, of an NSF group who have barricaded a subway station. "Get the hostages out if you can, but make sure the NSF learn that human shields will not work against UNATCO".

UNATCO HQ is a house divided. You're free to talk to the secondary characters whom work there between missions. General Sam Carter, a war veteran, runs the armoury. He's not happy with the way UNATCO's mission is being handled by the higher-ups, but affirms that the majority of people working in the building – the civilian staffers and the boots-on-the-ground – are "24-carat gold".

Wander down to UNATCO's bottom level, however, and you'll find the holding cells; several hold NSF prisoners. You're forbidden to talk to them (though you can), and later, one of the game's primary antagonists (a shady government higher-up) arrives to conduct the interrogations personally. Follow him surreptitiously to the cells and you can watch his 'interrogation' of the captives – who are, it's made clear, US citizens with families. The interrogation begins with carrots, moves on to sticks, and ends with murder. The government representative coldly rationalises his actions as "responding to a threat". The doctrine of the Bush and Cheney administration is carved deep into the foundations of UNATCO HQ.

"We may not have the premeditated lies of Deus Ex, but we do see extraordinary feats of storytelling when governments overstep or mis-step", says Pacotti. "To me, at least, some of the malaise of the Deux Ex dystopia has been present during the years after 9/11, during which torture, mass surveillance of civilians, and disregard for due process have all been touted as necessary for fighting terrorists. It's the story of totalitarianism nicely wordsmithed by the West and provided free of charge back to the rest of the world".

But if its treatise on terrorism was Deus Ex predicting the 2000s, maybe the best measure of how much times have changed since the game's original release is the fact that mass surveillance of a civilian population, while a fact of life in the game's universe, doesn't even earn the honour of being a major plot point. It's almost relegated to a lone (if chilling) Easter Egg, a hidden encounter that is easy to miss altogether if you aren't actively looking for it.

About midway through the game, JC finds himself quasi-abducted and wakes up in the secret mansion of Illuminatus Morgan Everett. It's one of Deus Ex's many non-combat moments. JC's objectives are to meet Everett, learn about the Illuminati's plans for the world, then meet his pilot Jock at the helipad so that he can fly off to his next mission. But if you decide post-meeting that you'd rather take five to do some snooping, you might discover the code to an otherwise impregnable blast door. Behind it sits a computer running an artificial intelligence named Morpheus.

Morpheus, as it explains itself to JC, is a retired prototype for part of the ECHELON network: a gigantic, automated spying system built to intercept and analyse phone conversations, emails, faxes and other forms of communication from around the world. In the game, Morpheus has since been replaced by more advanced AIs (Daedalus, Icarus and possibly Oracle). Now it is kept by Everett as a techno-curiosity to amuse house guests. Its party trick is telling people their life stories, harvested from the digital footprints they leave online.

"Human beings feel pleasure while they are watched," it says, without emotion. "I have recorded their smiles as I tell them who they are".

"Some people just don't understand the dangers of indiscriminate surveillance", JC replies.

This unhappy piece of future-gazing was written at the end of the '90s, before Facebook, before Twitter, before smartphone apps that recorded your movements via GPS with your one-tap consent. More unsettlingly, Morpheus dismisses JC's cynical response ("no-one will ever worship a software entity peering at them through a camera") as naive, positing that "the need to be observed was once satisfied by God" and that "the human organism always worships. First it was the gods, then it was fame: the observation and judgement of others".

That's Morpheus, a fictional artificial intelligence, predicting the web-born mentality that drives Facebook-stalking and pushed the Mail Online to become the most viewed online newspaper in the world, off the back of stories about D-List celebrity affairs and cellulite.

"In the Morpheus conversation, though I personally had no inkling that something like Facebook was on the horizon, I started seeing a very clear personal connection between human beings and the 'data mining' of the [Morpheus] AI", says Pacotti. "I think there is this fundamental human need to be known, understood, and therefore assigned a proper place. Even among a group of teenagers on Facebook, this involves a certain ceding of power, whether to a group of peers or to our software overlords".

If this article had been written ten years ago, it would have been about war and the lengths that a hypothetical future government might go to in the nominal defence of the Homeland. Deus Ex would still have been ahead of its time, but rooted in the physical and segregated from the life of the average citizen; we'd be talking about the military augmentation of soldiers through the Future Soldier programme or the abuse of captured enemy combatants and illegal rendition, not mass surveillance and the individual right to privacy.

But even after Guantanomo failed to close, even after the term 'Black Site' entered the vernacular and can now be bandied around in TV shows like Homeland and The Blacklist without making us sick, Deus Ex's other themes remain salient. The hero facing off against the corrupt heads of the serpent with Plasma Rifles and GEP Guns is still good video game gloss, but the backing music – the rich getting richer at the expense of the poor, the distrust of the government – resonates more than ever. So what has changed in the 14 year interim? What would Deus Ex have looked like if it had been made today?

"Nothing is quite right about the world of Deus Ex", says Pacotti. "Like all fiction, the gameworld is prone to exaggeration – from the luridness of cybernetic implants to the fierceness of laboratory mutants – but when I try to put my finger on something that is dead wrong, I have a hard time.

"One issue that occupies more of my attention these days is the falling economic worth of human beings. Globalisation simply continues industry's search for cheap resources and cheap labour, as disruptive as it may seem in the West – and might well work its mischief long before the timeframe of Deus Ex. The more apocalyptic change is automation. The middle class is disappearing because mediocre human intellects, which previously could be effective at organising, say, a filing cabinet, simply don't 'add value' where they used to. The conspirators of a re-imagined Deus Ex would need to be more cognisant of this shift, I think.

"The tone of [the game's] idea – a [domestic] armed uprising in the US – doesn't feel quite right today, yet all of the same tensions are present. Accusations of a conspiracy between big business and government, anger at the US allowing itself to be led by other countries, severe wealth disparity, armed standoffs between ranchers and the government, secession movements (like the recent one on Colorado)... A slight shift of focus, and the future could still turn out like Deus Ex after all".