The same holds true for gameplay, which runs even deeper than the narrative. BioShock is technically a shooter, but that classification does not do justice to the diverse hybrid of combat, strategy, role playing and puzzle solving. Enemies can be defeated in an almost infinite number of ways, from the violently straightforward to the defensively strategic. The choice is always yours.

If you like the fast and frenetic style of Doom, for example, you can rush through this game shooting everything without a second thought. Only in addition to traditional weapons like pistols, grenades, arrows, flamethrowers and rockets, you'll also be equipped with the plasmid powers you've spliced into your genetic makeup. Massacring monsters with a blast of fire, ice, wind, electricity or - why not? - angry bees is a hell of a lot more interesting than filling them with bullets. Watching that stuff erupt from the flesh of your character's arm is pretty gnarly fun, too.

But BioShock encourages thinking above all else, providing you with plenty of tools to fight smarter. You can combine plasmids for creative attacks. You can set traps using proximity mines and trip wires. You can purchase special incinerating or electrifying ammunition for your guns. You can hack and rewire a security bot to join your side. You can conjure a decoy to distract enemies. You can enrage enemies to rip each other's throats out instead of yours. You can even hypnotize the game's iconic baddie, the Big Daddy, to protect you instead of the Little Sisters. The list goes on and on...

And yet somehow, there's more, as the game also includes some relatively robust RPG-style character development. Special skills (everything from tougher armor to quieter footsteps) and upgraded plasmids can be purchased with Adam, the genetic substance stolen from murdered Little Sisters. Your decisions, therefore, affect not only your ability progression, but your morality as well... and which ending you see.