When developers decide to create a game set far off in the distant and often bleak future, a plethora of options instantly become available to the creative minds behind the scenes. But more often than not these developers miss the opportunity to construct a truly believable world. Thankfully, this hasn't happened with Ion Storm and mastermind Warren Spector, as the long-awaited Invisible War stands head and shoulders above the rest of the pack.

The original Deus Ex turned many heads and as a result landed several awards for its innovation and superbly crafted story. It would have been dangerous for Ion Storm to drastically change the formula that made Deus Ex such a critical hit, but at the same time the follow-up has shaved off some of the RPG-inspired depth. Things are a little more accessible to gamers who have yet to plunge into a first-person action game where shooting everything that moves is not necessarily the way forward.

Many publishers harp on about how making decisions in a game really does affect the outcome. In Invisible War though, this is more than just marketing spiel, it's what makes it something very special indeed.

The story revolves around various warring factions (some good, some bad, some very mysterious) vying to take control of the city of Seattle's main interests. Along the way members of these factions contact you with information about these other parties as well as offering you advice on what you should do next. Within 30 minutes your head will be spinning with all the possibilities that have already been presented to you. But how you do - or don't do - things is entirely up to you, and this is what separates the Deus Ex series from the rest of the action adventure gaming world.

Life begins in the Tarsus Academies, which Ion Storm describes as a global chain of schools that provides education and training for a select few. Courses include academic as well as physical, technological, weapons and psychological training. Each student is matched with a sponsoring corporation, revealed on graduation, when the trainee joins that company's covert operations. And it's all about covert operations.

Played through a first-person perspective, you make your way through the city meeting the local inhabitants. These include everyone from government guards and scientists to underworld hoods and cult-like warlords. Some have a story to tell while others will get straight to the point and ask you to carry out specific objectives for rewards. As you pick and choose your way through the opening levels of the city, you're subconsciously choosing the side you're going to fight for. But if at some point down the line you decide you've been conned, you can switch teams when good times go bad. The word 'open-ended' doesn't do this game justice.

After a lightning-quick character creation sequence, the story begins right from the word go. There's no wandering around aimlessly waiting for the first key set-piece to take place. You're in your nice futuristic-looking apartment throwing a basketball around admiring the incredibly realistic physics as a terrorist attack kicks off all around you. From there you're thrown headfirst into the story.

A hologram turns itself on and begins to tell a little bit of backstory for those who are unfamiliar with events of the original. You're given your first objective and from then on you're plunged into a story that wriggles with more twists and turns than a worm that's been chopped in half. And seeing as one of the game's main features is its story, it only seems fair that we keep quiet. You'll thank us later. Another important feature is the head-up display (HUD) system, and this plays a vital role in keeping things simple. As you can imagine with a game littered with literally hundreds of little objects to acquire, things could become a little difficult to manage without a well-thought-out inventory system. The last thing you want to be doing is pausing the game every time you come across something new. A quick press of a button brings up a unique HUD, and making room and ditching unwanted gifts or spent ammo clips is easy.

The left side of the HUD displays items such as your weapons, ammo clips, bars of food and cans of drink (providing a little energy boost), while the right side displays your current biomods. The red bar on the top left of the HUD is your energy and the blue one on the top right lets you keep tabs on your biomod energy. All of which is very helpful.

Biomods are another major feature brought back from the original. After receiving your initial briefing at the opening of the game, you're given a couple of biomod canisters to get you on your way. Essentially these are improvements to your body that enhance certain abilities. The areas of the body enhanced are truly down to you.

You can become invisible to machinery such as security cameras, robotic guards and lasers that sweep the floor looking for intruders. If becoming invisible to enemy robots and security systems doesn't float your boat, then you can enhance your body so you can run faster and take more damage. So rather than creeping past the enemy you can just make a mad dash for it and chances are, you'll make it to the other side in one piece. This degree of freedom also means that should you play the game through again, it'll be different from the first time you saved the day if you choose to enhance different areas of the body.

Not all canisters are easy to come by, though. Sure, you might be given the odd one from time to time and find another lying in the corner of a dark room, but for those gamers among us who can't help themselves but search out every little secret, there'll be a few surprises in store. Without giving too much away, scattered around the game you'll find a few black-market biomod canisters, which do illegal things to parts of the body other legal canisters cannot reach. The secret mysterious race known as The Omar will sell the odd one to you, but you'll have to save your credits like the bailiffs are coming round for a visit. Of course, as we all know, items on the black market don't come cheap at all.

Controlling your character and manoeuvring him or her through the world is easy. The only problems we encountered in this area were when all hell broke loose and a savage firefight caused us to look around quickly while making a run for it. Ion Storm describes the game as a first-person shooter, but it doesn't feel like one to us in this area. Being able to adjust the sensitivity of both sticks does help, though.

Invisible War is a huge game with many different endings to uncover depending on how you play it through. And if you played the original then you'll find out a few things about what really went on there, too. Again, it's very story-driven but lengthy cutscenes are few and far between, thankfully. The story is told in conversation as you meet people and make your choices about which path to follow. If you've had enough of driving and sports games over the festive period, you could do a lot worse than losing yourself in the deep, dark and disturbing world of Deus Ex. Just make sure you tell everyone that you won't be right back, as this'll eat into your life, leaving you lying awake at night wondering who to trust - even your mum.

1. Beautifully put together
2. Mega-detailed game world
3. Great story

1. Controls could be smoother
2. A bit overwhelming at times

Power
There's always a lot going on, but Xbox pumps out the horsepower to handle it.

Style
From the story to the locations, lon Storm has created a stunning game world.

Immersion
The well-crafted plotlines and characters will suck you in and swallow you whole.

Lifespan
A whole universe complete with a thousand different paths to explore and numerous worlds to visit.

Summary
A mind-blowing, expertly crafted experience that action fans would be foolish to miss. It doesn't get any better.