There's a dark story twisting its way through the world of Rapture and the game throws emotional choices onto your lap. Once you've defeated a Daddy and the Little Sister's crying next to the smoking shell, you've got a choice on your hands - save the little girl, taking one good thing from this dirty mess back to the surface, or harvest her, taking maximum Adam to tone your powers, but killing the child in the process. The consequence of either harvesting or saving a Sister only really affects what ending you see.
Like Valve's Half-Life 2, Bioshock doesn't rewrite the rules of first-person shooting, but it exceeds in both narrative, world and gameplay - which, despite how many times you may have fired a machine gun or built up your stats in the past, makes for more single, standout moments than we've had in a long, long time.
Moments like the countless twists and set pieces in Bioshock's fantastically well-written plot.
Or the huge variety of combinations you can play with, or the many interactions with the Big Daddies you'll have, like accidentally catching them in your crossfire and having to leg it across a whole level to escape their screen-shaking charge.
The world of Rapture is almost enough to make Bioshock an exceptional experience on its own. But the fantastic role-playing elements, standout scenarios and truly mental character encounters make it extra special. An experience of this calibre only comes around every few years and should be played by as many people as possible.
Engaging, immersive, repulsive, beautiful and challenging on every level, all at the same time. The bar has been raised...