Rare are the games that, rather than just letting you play them, actually make a point of playing you.
When BioShock rolled out on Xbox 360 almost a decade ago, players caught up in the pre-release hype thought they were getting a game designed to question the morality of killing in play. But expectation provided a smoke screen behind which one of the greatest plot twists in recent gaming history slipped through unspoiled.
Pre-release column inches described the 'Little Sister quandary', which forced players to decide whether to help or harvest sinister-yet-innocent looking girls roaming the halls, but BioShock on the whole was about so much more.
What if, many days into your adventure, you were forced to question every single move, every single decision you'd made from the moment you first sat down on your sofa? What if you can't even trust what the game itself is telling you?
Laymen may assume BioShock was a massive hit because it featured guns, guts and glory; in reality its impact was magnified many times over because of the world it took place in - an underwater metropolis more fantastic than Atlantis.
The city of Rapture - a largely abandoned, sodden and sour landscape trapped in the late 1950s - was not typical fodder for a triple-A title. What creative lead Ken Levine and his team managed to do was translate the propaganda of the early days of the Cold War – with its mixture of blind optimism and fear - and turn it into a physical world.
As you step into the capsule that takes you down into the depths of the ocean, every moment is designed to impress; from the Chicago style skyscrapers piercing through the water to the flickering neon lights, echoing the ambition and modernity that went into its construction. Rapture, however, is no paradise.
The city's descent into madness is drip fed to the player, both through audio diaries littered across its landscape and the few spectres who remain. Their make-up is smudged, their hearts are cold, and their bodies addicted to ADAM - the cell-forming substance that hands players the ability to genetically modify their bodies and take on all kinds of special powers.
From firing lightning bolts to hypnotising and even enraging your rivals, ADAM and the powers (or Plasmids) it granted users were sold to Rapture's population much like a new iPhone is to people today: upgrade, upgrade, upgrade. This need to better's oneself physically and mentally is built into the city's very DNA, with Rapture's creator - Andrew Ryan - fuelling its creation to play host to society's best and brightest. The echoing of other movements with a focus on eugenics is no doubt intentional, and evidence of Rapture's former totalitarian-like existence remains littered throughout its hallways.
Dilapidated though it may be, BioShock's delicate world - leaking water all over and its walls quite literally drenched in blood - almost begs to be left untouched. While most shooters program you to fire at anything that moves from the word go, much of BioShock's charm comes from creeping through its corridors, taking in what life that remains and sifting through the fragments of the city's short history.
The overarching feeling as you gaze upon this dystopia, however, is how it represents the notion of being promised the world on a silver platter and delivered a turnip. Indeed, it's arguable that BioShock's message of cynicism and distrust would play to an even bigger audience today. At a time when, on both sides of the Atlantic, the general population appear to distrust their politicians and despise the system that keeps them in place, a game that directly addresses the notion of people being lied to - of a greater purpose being hidden beneath the surface - would draw in quite an audience.
This is the great double play BioShock pulled off with aplomb: the surface story of a business magnate's desire to create a utopia that ultimately ends in ignominy helping hide the deeper tale of what is effectively the game's tutorial double crossing the player, almost at its conclusion.
Surviving a plane crash in the middle of the ocean, Atlas' is the first voice the player hears afterwards, and his soft Irish tones serve as a calming presence throughout. He explains how to play, how to stay alive, how to compete in Rapture. Plot twists are by no means rare, but to take a player's initial point of contact and turn them into an adversary is akin to drawing all the oxygen from the air and tasking you with breathing.
In the intervening years, flipping play on its head in this manner has become BioShock's signature style, but it's a trick especially difficult to pull off twice. It's also a factor that has made BioShock rather hard to follow up.
BioShock 2, though acclaimed by many, was considered too similar to the original in terms of gameplay to be considered a classic in its own right by others, while BioShock Infinite - set up in the sky rather than underwater - was too repetitive to keep hold of all of the fans that first trip to Rapture had amassed. That's not to suggest the first BioShock was itself the finished article, in the years after its hallowed debut critics have been keen to point out its misjudged final hour and FPS elements that are a little one dimensional.
The game's legacy, however, lives on, if only because developer Irrational Games' original aims were far broader than merely depicting a high-def firefight. BioShock is instead primarily a tale of the breakdown of society. It's a story of greed, of addiction, and the erosion and ultimate destruction of humanity. It's also a title that teaches the player to question everything they're told, even when it's the game itself that's telling them.