Adam Jensen, the perfect cyborg, is wrestling with a vending machine. It's not refusing to serve him orange drink, it's refusing to fit through a door.

He is, as I play him, the worst chief of security in the world. He works for Sarif Industries, the company who make his robotic arms, and indeed the company who gave him his robotic arms after he failed to protect the company from a major assault and got himself shot in the head. Why this caused his arms to fall off is not yet clear.

Jensen finally gets the vending machine out onto the roof. He has a plan: “Maybe if I throw this vending machine off the roof...” The plan ends there.

He's inside gang territory, trying to make it to a door at street level. He decides to use the surprising development of a vending machine falling out of the sky to distract the gangsters, so that he can drop down and get to the door without attracting attention. A sort of pepsi ex machina .

Jensen hurls the vending machine arbitrarily and tumbles off the building after it. His Icarus Landing System kicks in, floating him safely towards the street below in a dazzling ball of golden light. When the vending machine crashes to the ground, the armed gangsters nearby all look at it in surprise. Then they look at the dazzling ball of golden light floating down to land across the street, and they draw their guns.

Jensen gets up, looks at them for a moment, and dives for cover. As he draws his custom-modded silenced 10mm pistol, the nearest gangster walks over, looks down at him and says “Hey. Get lost.”

Jensen holsters his gun and walks sheepishly to the street-level door.

The Deus Ex games are first-person shooter RPGs that let you approach your objectives in a way that suits you: direct violence if you enjoy it, stealth if you don't, and throwing heavy objects around if you like getting caught, beaten and shot. Despite a sequel in 2003, the first is still considered by me, this magazine, and a lot of our readers as the best game ever made.

Human Revolution is a prequel: a global conspiracy thriller set at a time when replacing your body parts with high-tech prosthetics is a violently controversial new trend. It is, I guess I should mention, the best game I've played in four years.

So I'll talk about it in three parts: firstly, everything that Human Revolution recaptures about the original Deus Ex (quite a lot). Secondly, the few things it misses (not that much). And lastly, what it does better than the first game ever did (amazingly, loads).

The main thing Human Revolution gets right is giving you options: every mission gives you a labyrinth of ways to get to your objective. The man-sized air vent is a cliché, but honestly, it never stops being satisfying to bypass a locked door or a group of enemies.

The pleasure of that freedom is that it leaves major elements like pacing, challenge and variety up to the player. If stealth gets too hard, you can find an easier route. If you're bored of vents, you can open fire. And if your ears are still ringing from the last gunfight, you can slip through the next area quietly.

And these are just the routes the developers have planned. The soul of Deus Ex is in its systems: simple sets of rules with no scripting, no exceptions, and no accounting for what the player might do with them. If you can pick up a box and stack it to reach an alternate route on the first level, you can stack every similar box in the game and reach anywhere physically possible.

Human Revolution has that exact system – though the more cluttered levels mean it takes a while to learn which objects you can move. It makes up for that by interlocking it with other systems in entertaining ways: the slick, surprisingly natural third-person cover system lets you hide behind any vertical surface, including the ones you've placed there yourself. The AI in friendly areas now has a flimsy concept of suspicious behaviour, and you can build a hilariously conspicuous cardboard-box secrecy fort around a security terminal to hide your criminal hack. Even turrets are now physical objects that can be picked up, moved and thrown.

I called mine Gunther. I was only able to get to his control console by shuffling past him behind a cardboard box. Cardboard doesn't block a turret's bullets, of course, but it does block vision. In a potentially fatal game of What's the Time Mr Wolf, I'd shuffle the box a few feet closer to Gunther each time he swivelled away, and duck behind it when he looked back. Once I hacked into his controls over the shoulder of a sleeping guard, he was my friend for life.

I carried Gunther into his own control room to let him mow down the guy who should have been monitoring him. Then I sat him at the top of a ramp to pelt fire at a whole gang, while I snuck up behind them and extended the fist-chisel blades of my robot arms.

When a minigun guard destroyed Gunther a few fights later, it hurt. Because he exploded, and I was using him as cover at the time.

Page 1 of 3. Next: Where it falls short, and what it does better .

Like Deus Ex, Human Revolution is still a linear series of levels. But also like Deus Ex, the levels themselves feel like places. When there's a facility to infiltrate, it feels like a real building, with multiple floors and wings to explore in whatever order you like.

There are two differences, one positive and one negative. The positive one is the city hubs: both games have large, open urban areas you return to after several missions. Human Revolution's are bigger, more complex and far, far richer with things to do and secrets to find. They do have in-game advertising , but I can't say it bothered me in context.

The negative one is more subtle. Quite a few missions in Deus Ex, including the famous first level on Liberty Island, let you explore the grounds of the mission location before entering the main building. Only a couple allow this in Human Revolution, so it doesn't always have that same dizzying level of freedom the original did.

There are two other areas where Human Revolution doesn't entirely pull off what the original achieved. Firstly, the direct approach is a little too effective. While there are bots and turrets to hack, gas barrels to blow open, and photocopiers to throw at people, subversion and improvisation are rarely the best way out of a situation. Shooting someone in the head with a silenced pistol is more consistently viable here, and that can undermine the pleasure of coming up with a brilliantly convoluted solution.

The last problem only comes up four times in the whole game, but it's an odd one. There are boss fights. They are terrible. And they cannot be avoided. The game is so conflicted about this that there's even a Steam achievement for completing it without killing anyone, which apologetically adds that boss fights don't count.

Yes they do, guys. Not for the achievement, maybe, but if you want to play stealthily, evasively, or cleverly, there are four times in the game when you just can't. It's completely incongruous with the rest of the game.

That's it: those are the only three things that really bothered me. If all Human Revolution did was capture that much of Deus Ex's genius, with so few flaws, it'd be incredible. But we're only just getting started. It adds masses more to what Deus Ex started, polishing its roughest edges and adding new ones that fit with them beautifully.

The cover system immediately improves the two main things you spend your time doing: hiding and shooting. Deus Ex made stealth viable by making your enemies hilariously short-sighted. Human Revolution makes it viable by pulling out to third-person every time you hold the cover key to hug a wall. It shows you exactly which directions you're hidden from, and lets you see out from your hiding spot without exposing yourself. It's not realistic, but it means stealth works all the way through a game where enemies are sharp, aggressive, and can kill you in a second.

Combat then becomes a tough but polished cover shooter. You can blind-fire or peer out for an accurate shot, and enemies intelligently find their own hiding spots and do the same. Almost every weapon feels punchy and satisfying – particularly the spectacular knockback of the nonlethal PEPS gun – and there's a lot to choose from for any play style.

Until I knew enough about the plot to know who deserved to die, I stuck to non-lethal weapons. This became a problem when a key conspirator sent a dozen armed guards at me in a dead end. Bullshit, I thought – there's no non-lethal way out of this. All I really had was a puny close-range taser and a lot of grenades.

Hmm.

I was killed, brutally, but on my next attempt I had an idea. The moment the guards flooded in, I threw a concussion grenade at the left hand side of the group. Concussion grenades do almost no damage, but send people flying. Everyone on the left was flung into everyone on the right, piling them all up in a small area. Which is when I threw a riot gas grenade into the centre of the clump. No one got up.

Augmentations make both combat and stealth more interesting. And cleverly, most of the stealth augs do it with pure information. With the right upgrades, you can see the fields of vision of everyone nearby on your minimap, the radius of every suspicious sound made, and the positions of all nearby enemies, bots and security terminals.

I honestly had more fun with a pure stealth approach in Human Revolution than with the entirety of Splinter Cell: Conviction. It's heart-skippingly tense, deliciously high-tech and slick to control.

Combat augs cater to a lot of different styles, but melee is where it gets fun. Any time you're close to an enemy and have at least one cell of energy – your aug-fuel – you can kill or knock them out with the press of a button. In third-person, Jensen does swift, forceful, terrible things to people with his robot fists – or his robot fistchisels, if you've held the button down for an execution.

I'd imagined these moments of cinematic pain-porn as a necessary evil to make a smart game sell in today's mainstream market. I'm not sure what it means about me, but I ended up finding them the most enduringly satisfying and hilarious interaction in the entire game. I was still watching them with a contorted mix of horror and delight right to the end. The moves are so jaw-hangingly violent that the switch to an external perspective doesn't jar: you're actually glad of the distance.

There's even an augmentation that lets you take down two enemies at once, which makes planning an attack a fascinating logic game: “If I stand here when I headshot that guy, I can take both his friends in melee, then run to his body and drag it through the door before the camera looks back.”

When that takedown involves physically picking one guard up and throwing him on top of the other to skewer them both at the same time... I'm not proud of it, but this is might be my entire concept of fun.

Page 2 of 3. Next: Globe-trotting and word-fighting .

Hacking is immediately smarter and more involved than in any previous Deus Ex game, and it plugs cleverly into the aug system: it's genuinely tough to decide whether you'd rather extend your time limit, or reduce the risk that the system will detect your intrusion in the first place.

In general, too, decisions about how to upgrade yourself are agonising. It's like picking a superpower – each one of the 60-odd options seems like it would solve all of life's problems. Cyber lungs? That could revolutionise my balloon animal career! X-ray vision? I'd never eat an orange Revel again! One even helps with the new conversation system, scanning brains and releasing pheromones to help make you more persuasive.

With or without augs, dialogue in Human Revolution is a game. You're trying to talk everyone from thugs to world leaders into revealing a conspiracy they're all complicit in, and there's a knack to that.

This is conversational combat, where you choose between three possible responses at every stage, depending on which you think will be most persuasive to them. It's not about light side/dark side: you have to pay careful attention to exactly what you'll say, and whether your argument really makes sense. It's absolutely possible to lose, forcing you to find a different route to your objective and permanently depriving you of useful information.

Those stakes, and the heart rate spike they trigger, make these feel like the real boss fights. When you face the final villain, your options aren't which glowing weak spot to shoot – they're 'Appeal', 'Critique', and 'Extrapolate'.

The full story is vast and complex, crammed into every corner of Human Revolution's world. Every apartment you break into, every secret room you find, every rooftop you clamber across has little scraps of personality and history to read and interpret. It's a story-junky's blissful overdose.

There's a piece of information to be found in the first room of the game that isn't explicitly revealed to you until the end of the game 27 hours later. And more than a few times, one word in an email will trigger a headtingling revelation about the hundreds of subtle ways Human Revolution sets the stage for the original Deus Ex.

Human Revolution's world is also one that reacts to you. There are a few times when critical characters can't be killed, but I was more often surprised when they could: when an experimental keypress caused me to put my fist-chisels through my ex-girlfriend's mother, for example. Conversely, the seemingly inevitable death of at least one major character can be averted, and some decisions made in the middle of the game don't play out until the end.

The places your missions take you are gorgeous. You start in Detroit, a dim vision of an industrial city collapsed and revived one too many times. Later, the Chinese metropolis of Heng Sha is genuinely like visiting a new country. It's a hazy mess of neon, a half-vertical city with no distinction between rooftops and streets – large, bewildering and excitingly foreign.

The game could do with one more city hub to flesh out its vision of the future – we glimpse the dazzling utopia of Heng Sha's upper layer through windows, and the dense skyline of Montreal from a helipad, but never quite get immersed in either. What we do see is uniquely beautiful, though: each art style bold, clean, and distinctive enough to be worthy of Mirror's Edge.

It's ridiculous that a game which captures so much of the original Deus Ex's genius has also managed to combine it with an exquisite art style, elegant polish, and such an easy cinematic cool.

Is it as good as Deus Ex? Not quite – that slight shift away from improvisation and wide open spaces stops it just short. But it is absolutely the Deus Ex of our age, a genuinely worthy prequel, and a game that puts almost everything else in the genre to shame.

It's also a game built with a respect for its players. At every stage, Eidos Montreal have asked “What if the player wants to do this?” And instead of answering with “Put an invisible wall there to make sure they can't,” they've kept working on it until you can. They've kept working on it until you're rewarded for original thinking, instead of slapped in the face and shoved back on the tracks.

I don't know about you, but I've been waiting a hell of a long time for a game like that. I've been humping low walls, shooting NPCs and trying to smash down locked doors for eleven years, and every game has broken, buckled or refused to react until now.

The reason nothing has replaced Deus Ex might not be that no one understands it. It just wasn't a huge commercial hit, so how can anyone justify such a big investment in something so open-ended?

Eidos Montreal's spit, polish and fist-chisel punches have found a way, and I hope we won't let it be the last time for another decade. I'd love to see Human Revolution show that smart can sell, and that gamers love freedom more than they love firing assault rifles at the Middle-East.