A strong, if heavy-handed in forced direction, opening follows with a rapidly-cooling ardour come the following few hours exploring the streets of Detroit.

For those of you to whom the name Deus Ex conjures vague second-hand accounts of what has been billed as "one of the greatest games ever" by some, you needn't click through to Wiki to avail yourself of background. Human Revolution operates as a standalone title, wearing the mechanics of its ancestor but not requiring inherent knowledge of them.

You play Adam Jensen, security head at Sarif Industries, investigating an attack on HQ months earlier that left you half-dead and now partially cyborg. Unravelling those threads takes the form easily explained with a few key terms: first-person adventure, RPG and stealth elements, multiple routes and side-quests, future sci-fi, Blade Runner.

The brief overview of the plot and story is as much as we're going to explain, as much to avoid spoiling surprises for you as out of respect for the developer. But just to touch on the story though; the angles aren't so clearly defined as you'd imagine, and it elevates itself above any cliches you'd believe fitting of a futuristic thriller.

So that's the central narrative, linked by big chunky missions full of talk or firepower, but it's intercut with more of the same in optional side-quests. Converse or shoot - it's all your choice, though you'll spend more time exercising jaws than breaking them.

The main story offers great hooks with each new twist, but you won't find the side-missions lacking either. Each mission has multiple objectives, at least some of which are in the same general area of the next main checkpoint, giving you the option to adopt or drop your next destination with minimum fuss. Even those objectives off the beaten track help you learn the city's layout.

We mentioned Blade Runner before. A classic detective archetype exploring futuristic rain-torn dank cityscapes which thrive with life and possibility is too strong an image to shake, and comes with a degree of expectation. Deus Ex is known for creating a believable, thriving cityscape. However, this isn't the case for Human Revolution, and provides the game its first big stumbling block.

The game's closest living relative today, in terms layout and matching the personality of the locale to its protagonist, is Arkham Asylum. A tightly contained world in which you're free to explore, honeycombed with hidden paths, side-quests and NPCs to converse or fight with, expanding as objectives and new abilities come into play.

Yet Deus Ex fails in crafting a vibrant metropolis. The stitching between city streets is too obvious not to ignore, not to excuse. Invisible walls are all too obvious and there's a lack of diversity, as you see the same collection of faces at every street corner, hear the same lines of dialogue all too quickly, and see the same shop displays regurgitated. It's Scooby Doo goes sci-fi. You're instantly disconnected from any sense of immersion.

Go digital however and its a different story. Any hackable computer will give you vast swathes of dialogue between emailers. Some pay off into the story proper, others are inconsequential, but all flesh out personalities that you may not even meet face to face. It's brilliantly voyeur and a handy media log copies every written document for your later perusal. Then there's the story flashpoints - but we'll get to that in a moment.

It does means your enthusiasm for the conceit of a thriving city, initially anyway, is heavily dampened. Yet while a long time in coming, frustration finally erodes into realisation as the game delivers a grand-scale visual pay-off, and some of the early negativity is washed away.

Aside from the most obvious locations, map guides don't list individual streets or housing courts - meaning a good while is spent looking to signs at corners and mapping places in your head. Initially a chore, it ultimately is more satisfying and organic, walking to a street by memory rather than checking the map or using GPS functionality.

Player choice is much lauded within games, but Deus Ex is one of the few titles that manages to claim success of such a grand ideal. It's one of its greatest strengths and the mechanic most central to its beating heart. Talk, coerce, knock-out or kill. Four simple decisions that play out much more naturally and dynamically within Human Revolution, and is one large slice of the "RPG" portion of this action-RPG.

Conversation is king, and you'll have a better experience for engaging wholeheartedly with it and connecting with the world, as it gives context to the gun battles that intermix infrequently with gameplay that's more about exploration and stealth. Everything happens for a reason in Human Revolution, and its more enjoyable if you know why.

The biggest hook of these are the conversation flashpoints, key talks with characters central to story progression. They take the form of multiple multi-branched dialogues in which you try and extort or convince your contact into either release information or help you. Through a combination of great writing, superb voice acting and convincing facial and body language, these scenes are the highlight of Deus Ex.

There's no clear right or wrong - although a later augmentation will let you "read" your contact to lead conversation where you need it - and as a result exchanges crackle with energy and uncertainty. You're engaged so heavily that every frown or dismissive shrug is a punch to the guts; failure to succeed forcing you to seeking alternative, more physical, measures.

And that's the real success and one that's endemic to Deus Ex. Although the arrival (and inferred importance) of such dialogues are too heavily signposted, their fallout is not, and the setup is fascinating. The conversations are as charismatic as their outcomes are coldly calculated; you know what's to gamble in each but you're never aware of what there is to loose.

Entire side-quests and secondary objectives may be swept off the table, while after-effects can ripple out and come back to haunt, or help, you later. You simply don't know. To reveal is to spoil, but it does need to be said what a genuine pleasure it is to investigate how a developer has been so meticulous in designing areas to operate both as thriving pedestrian walkways and cunning labyrinths for illegal entry.

The ability to expand your choices in objectives at times lies solely with your arsenal and augmentations. The former can be lethal - care to name any standard FPS weapon and you'll find it here - or non-lethal in the form of tranquilliser guns, rifles or stun-guns. Non-lethal engagements won't raise alarms in patrolled areas, but can still be seen if there's a clear line of sight.

Despite an initial option offered at the game's start, lethal engagements are a no-go. Stealth is enforced, despite the choice. Bullet caches are limited to such an extent that scoring head shots are the only option to survive early on, and without armour Augmentation a few well-aimed blasts will turn you into a destroyed toaster. That said it's a good inclusion, ramping tension in the early section of the game, and ensuring you learn the benefits of patience and sneakiness.

Enemies in mission-based areas are Metal Gear Solid template, pre-programmed to follow a set patrol, and larger sweeping checks when suspicious. On normal its fairly easy to steal away when they're fully alerted; soldiers seemingly not trained to check further than your last known sighting. Locations are littered with cover-hugging boxes and platforms, and the context-sensitive cover button lets you easily sweep along multi-angled cover points. There's a dedicated list of augmentations - performance-enhancing and ability increasing tune-ups for your cyborg body - that track guards' cone of vision on your map, or let you see through walls to track their patrol routes.

Augmentations are a tech-head's wet dream and are also tantalisingly out of reach. Your full potential load-out has its own dedicated sub-menu, listing each augmentation by body part, with gameplay benefit and cost outlined on each, explanations instilling in us a giddy sense of desire.

Whereas you can buy ammo and health packs with credits from vendors (or loot them off bodies) Augmentations require Praxis Points, earned through mission completion, discovery of secret areas, or purchasing through clinics at escalating prices.

The result should be a custom play style dictated by the player's want, but we found we had to adapt augmentation upgrade choices to the story, rather than the other way round.

Being able to jump further, shoot sharper and generally make you into an unstoppable Robocop - a reference nicely alluded to in one instance - becomes secondary to increasing your hacking ability (enabling you to access higher security level doors and negating detection during hacking mini-games), increasing your lift capacity to shift objects aside to find air vents, or blinging out on stealth attributes to navigate through guard and camera heavy corridors.

Combat Augmentations can be show-stoppers, but their absence early on isn't felt due to the range of guns you quickly appropriate.

When you do start stacking bullets - at a point when you've had time to appreciate the combat system from a non-combatant point of view - you also start gaining weapon upgrades, increased precision and power, faster reload times, silencers and the like. Each is limited to certain guns, so tinkering with the arsenal and testing in the field offers another dynamic to gunfights. Going 007 with the silenced pistol brings back fond GoldenEye memories.

Come multiple Augmentations and increased arsenal later, you're still doing the majority of killing from behind cover, although sneaking between cover points is now second nature and gunfights, if you should choose, are much more fluid due to cultured confidence.

While it's by no means a grind to get there, its then, some hours in, when abilities start matching need, weapon upgrades are discovered, and a shift in locale eradicates some of the world-building issues that we had previous that Deus Ex comes back into its own. Thinking over our time with the game, it's hard not to dislodge that initial sense of disappointment, yet it offers sharp contrast to the considerable highs we strike as Human Revolution hits its groove.

Initially cold, distant, disconnected, Deus Ex gradually proves a sublime experience of player freedom and choice, negating initial negativity. By the nature of its branching storyline and open-ended approach to every situation it's definitely worth multiple play throughs, and afterwards discussion with your friends, as to what you did do, what you didn't, what you missed.

One thing we can tell you shouldn't miss is a chance to experience this title. It's likely the most diverse FPS you'll play in the coming months, and definitely the most engaging story you'll take part in this year.