In the design document for Metal Gear Solid 2, written in the months following MGS's success, there is a section explaining the concept of 'Absolute Evil in MGS2.' "Evil in Hollywood films," writes Hideo Kojima, "has always changed depending on the time in which the film's story takes place. In the American market, where audiences like to see good triumph over evil, the absolute enemy - be it a race, country or setting - has always changed with the values of the times."

Kojima notes that MGS2 will be aimed at this American market, and goes on to list some examples - Native Americans in Westerns, China in post-Cold War films - before writing that for the 1990s (i.e. now) this bogeyman is terrorism. As impressive as such prescience is, where Kojima's reasoning leads him can still take your breath away. "The evil in MGS2 is the American government."

Metal Gear Solid's enormous sales and critical acclaim are what every developer dreams of, but Kojima instinctively understood it came with a cost. His previous games had flitted between worlds and genres, but now he was duty-bound to make Metal Gear Solid 2. And this was an acute problem, because MGS was in part known for tricks and twists - Mantis, unique boss battles, breakaway sections like rappelling or imprisonment - that couldn't be repeated. Repetition is inherent to the concept of a sequel, so is that what people want from MGS2? Another Shadow Moses?

Metal Gear Solid 2 was developed for the Playstation 2, announced long before anything was seen, and anyone who was there will agree it was the most feverishly-anticipated game around. In the run-up to release MGS2's press campaign focused entirely on creating the idea this was a 'normal' sequel - the only section seen was the opening tanker chapter, featuring MGS's hero Solid Snake and sidekick Otacon.

It looked amazing, of course, and exactly what you'd expect from MGS2. And on the systems level the game is this straight sequel, and an absolutely superb one. It takes the basic principles of MGS stealth but changes everything by increasing the AI of the guards enormously, and being set in much more spatially complex areas. Guards can now see much further, hear more things, and during Alerts will work together in packs (rather than simply running towards the player).

This latter touch has become a hallmark of MGS, with soldiers moving in formation and appearing to work together. This adds enormous menace and a definite streak of realism to your pursuers - particularly when they clear rooms. If you've escaped detection but soldiers know you're in the area, they enter 'Clearing' mode and begin checking hiding places. You're in first-person view, because you're in a locker or something, and your map is replaced with a streaming camera feed of the soldiers examining around the hiding spot. It really is buttock-clenching, and an incredible finale to a clumsy escape.

Holding up guards is another new addition, which is lent a compulsive quality by their collectable dogtags - normally I don't like collectathons, but this one's irresistible.

This increase in threat is matched by an increase in the player's abilities, most importantly that weapons can now be aimed and fired in first-person view. In turn this leads to the implementation of area-specific damage on soldiers (at one point Kojima planned for injured foes to disappear then return with bandaged wounds). This then ties in with another great idea - after spotting the player, a soldier has to radio to trigger the alert, giving you a few seconds to rescue the situation. The radio is targetable. So if you're seen, one option is to switch to first-person and shoot the soldier's radio. After realising this, you can even take them out pre-emptively.

Consider too how the consequences of first-person aiming are thought-through. It's easier for players to kill or incapacitate guards. So now their bodies remain and will be spotted by other guards. So now the player can drag guards' bodies to hiding spots, and re-tranquilise them if necessary. The fiendish soon realise that a KO'd guard is a wonderful lure - in the right spot. Such elegant interplay of systems has to be admired.

These refinements went alongside a huge leap in visual detail and the ability to display many more characters on-screen. An early and witty example of the latter comes at the end of the tanker chapter, where Snake has to sneak around behind several hundred US marines listening to a speech, and taking photographs of Metal Gear Ray. Crawling under the projector, sneaking behind dozing guards and snapping away at Ray's amazing model is a great twist on the usual stealth setting, and coincidentally it's the last thing you do as Snake before MGS2 pulls the rug out.

The tanker chapter ends with Ray being stolen by Ocelot-cum-Liquid (don't ask), who sinks the ship during his escape, and we fast-forward two years. A figure makes his way towards the Big Shell, in sequences reminiscent of Snake's approach to Shadow Moses. He's called Snake by the Colonel but the voice isn't right and, even before the big reveal, there's a section where the player sees the real Snake ahead - rising up in an elevator. Before we even know his name, we know Raiden ain't a patch on Snake.

Raiden was MGS2's big secret, a character visually designed to appeal to people who didn't play MGS - specifically women. The first game's audience was largely male, and Kojima believed a good-looking young man would be a pleasant contrast to the gruff chain-smoking Snake.

But the true purpose was different. Before he was ever called Raiden, the character was known by the kanji (Ore) that literally translates as 'I.' Raiden was intended to represent the player, specifically the type of player who enjoys war-themed games like MGS. The events at the Big Shell closely parallel the events at Shadow Moses, with one big difference.

The HF blade is an iconic weapon for Raiden because it symbolises his emerging from Snake's shadow. The character's subsequent evolution post-MGS2 flows directly from this idea.

The first time you control Raiden, with his mask off and blonde locks flowing freely, the location is designed around a bespoke effect: lots of bird shit. Walk on it and Raiden pratfalls, an initially amusing animation that soon becomes a little tiresome as you search for the way forward.

It's a little thing but, boy, do they pile up. MGS2 in ways big and small undermines Raiden at nearly every turn, constantly reinforcing to both him and the player that he is not Solid Snake. The Big Shell is Raiden's first combat mission, and no-one misses the opportunity to remind him of it. When Snake meets Raiden he calls him "green" and "rookie." Raiden's first boss fight, against Fortune, cannot be won - and she taunts him for not being Snake. Where Snake stoically bore torture, Raiden ends up crying.

It is worth saying that none of this stuff is as overt as it may seem - and is compensated for by the fact that Raiden's first hours on the Big Shell features the game's greatest stealth sequence and one of its few memorable characters (a point we'll return to). The explosives expert of Dead Cell, a terrorist group that has taken over the Big Shell, has rigged each room with C4. Pete Stillman, a bomb disposal expert, is brought on-board with a team of Seals - who are promptly wiped out. Holed up with Raiden and Snake, Stillman confesses he's haunted by his failure to defuse a bomb that killed scores of civilians - but was brought on-board because he trained Fatman, Dead Cell's explosive expert, and knows how he thinks.

Stillman talks persuasively about the craft of explosives, which dovetails beautifully with the ingenious places that Fatman's bombs are hidden. In one of MGS2's most beautiful touches, each difficulty setting changes up the placements. And the objective is a perfect fit not only for stealth gameplay, but for showcasing the improvements MGS2 has made in environmental detail (bombs can be hidden behind open doors, or under floor grates), density (the labyrinth of crawlspaces), and dynamism (jumping between floors to reach otherwise-inaccessible spots).

This long bomb hunt, which covers most of the Big Shell's playable area, is without a doubt MGS2's high point. It encourages exploration and creativity, within complex spaces filled with serious AIs, and absolutely requires a stealthy approach - you can't spray coolant on a bomb when you're being fired at. The dramatic payoff with Stillman is great, and leads to a memorable callback later in the game, and everything's polished off with the fight against Fatman - which, while not quite as good, channels Vulcan Raven and adds a few new tricks.

At this point MGS2 starts to go in a different direction, focusing more on linear movement, boss fights and set pieces. It does this because MGS was structured in a similar way, which leads to one of the contradictions at the game's core: in many ways the Big Shell, while far ahead of Shadow Moses as an interactive environment, simply isn't as interesting on a thematic level, and this also goes for Dead Cell. In mimicking MGS, it feels like MGS2 often does itself a disservice. And whether you think this is deliberate or not all depends on what happens next.

MGS2's plot goes into overdrive in the game's later stages, in a sequence of revelations and double-triple-crosses intended to confuse players. The Colonel starts saying odd things, among them an instruction to turn off the PS2. The game starts to 'malfunction' during an exciting boss fight, mimicking the usual 'Mission Failed' screen with 'Fission Mailed' and the action continuing in a small window.

Vamp is a big moment for MGS's world, as he irreversibly moves it from fantastical-but-grounded future military into the realms of vampires. The boss fight, however, is a good one.

The simulation is collapsing. Raiden is established from the first as a video game player, a soldier raised on VR missions like Shadow Moses to become as good a soldier as Snake. As this first 'real' mission begins to collapse he questions who and what is real, if anything is, and how much of his own personality is a construct. What he and the player share is a love of virtual war games, and an idolisation of their participants: Raiden thinks he knows combat because he's 'played' it. The character's origin as a child soldier is a brutal detail in relation to this, paralleling how such tastes often form young, over a decade before you would see Call of Duty action figures in Toys R Us.

So the Big Shell mirrors Shadow Moses because that's what it was designed to do - the Patriots, who control the AI system, made the sequel the fans wanted. It has the Colonel. It has similar action beats. It has a terrorist cell whose members mirror Foxhound in personality or action or arena setup - and of course it has that ridiculous twist where the first game's main antagonist, Liquid Snake, returns from the dead.

In terms of plot MGS2 is where things went off the deep end for MGS, and the series would never be the same. The Ocelot / Liquid Snake arm thing is too daft to be taken seriously, so much so Kojima would later retcon it. Solidus, the 'third son' of Big Boss who's apparently President of the U.S.A., is surprisingly under-developed, while Dead Cell are great boss fights but utterly forgettable personalities.

The question with Dead Cell being, of course, is it deliberate? The game being an AI construct is flagged from the start, in the weird way the Colonel speaks and a hundred other tiny clues. In MGS, the game over screen said Game Over while the VR mission game over screen said Mission Failed. In MGS2 the tanker chapter's game over screen is Game Over, while Raiden's says Mission Failed - and even contains data about the simulation. So would Kojima go to the lengths of creating deliberately flat personalities in order to suggest they're simply AI personalities? Perhaps that very thought makes you snort - after all, a bad character is a bad character. Postmodernism is a difficult subject because of irreconcilable choices of interpretation like this, and because it problematizes reality as well as reality's representation within an artwork. We could say the postmodern work is a work that questions its own medium, by abandoning traditional ideas of coherence or structure, and creates unexpected meaning (if any) through a kaleidoscope of conjunction. In essence this is the technique behind the collapse of the VR simulation Raiden and the player inhabit, and the big questions it raises about control and identity.

For necessity I'll simplify, because MGS2's presentation is designed to overwhelm a player as part of the effect. MGS' big bad guys the Patriots no longer exist in human form, but are now an AI that seeks to control human behaviour through controlling information in the digital age - the idea of 'memes' thus replaces MGS's 'genes.'

"In the current, digitized world, trivial information is accumulating every second, preserved in all its triteness. Never fading, always accessible. Rumors about petty issues, misinterpretations, slander...All this junk data preserved in an unfiltered state, growing at an alarming rate. It will only slow down social progress, reduce the rate of evolution."

In other words this is the war for the internet: freedom of information against privacy and control. And any attempt to impose information control by governments is akin to the plan of the Patriots, inasmuch as it will be designed to suppress anything counter to that government - and through this to shape the behaviour of their populations. It's not far-fetched, it's China, and in the future may yet be us.

The ultimate message of this is sterility. MGS2's collapsing world suggests that holding onto old ideas, in the sense of making a sequel just like the original, is a sure route to obsolescence. Our future as a species depends on new ideas. Even if the old ones re-cycled will shift several million copies.

MGS2's final encounter strips Raiden of all his weapons - all of Snake's hand-me-downs - and leaves him with a sword, a weapon Snake never uses. Trapped in a situation where there's nothing Raiden can do to 'win' - after all, killing Solidus will serve the end of the Patriots - he nevertheless faces it without depending on Snake's example. This is really the only moment of character development Raiden has, because it represents the escape from his delusion that he's Snake - and, in a final cutscene, he tosses away a dogtag that bears the player's name. Finally he is free of living up to his idol, and thus of the audience's expectations.

Returning to MGS2's title screen after this moment, you find it changed: Snake's face, coloured red, is now Raiden's face, coloured blue. The colour of the 2 has also changed. The switch mimics the difference between lethal weapons (red) and non-lethal weapons (blue) in the game, highlighting one of MGS2's greatest improvements as it finally abandons MGS and Snake. MGS2 ends where it began, and everything's changed. But you got what you wanted. Right?