BioShock

The first of these is easy - a single round of electric buckshot provided at the spawn-point - but the level quickly pushes the player in other directions. One room is home to an iron safe, but it turns out to be booby-trapped, and electrified trap-bolts rope off the exit. Fortunately there was a telekinesis plasmid pickup on the way in, so the player coolly unhooks the bolts without touching them and redirects them to fry the safe, blasting it open in the process to reveal a crossbow with its own trap-bolt - good enough to put another jolt of electricity through the control panel. This is followed by a bit of light mountaineering, riding an elevator to a balcony and then dropping a level down onto a small platform to collect a static-discharge plasmid. Static discharge is like an electric shield, lashing out with a jolt whenever you're struck in melee combat - and the level inevitably introduces a few splicers - Rapture's warped citizens - to help with that.

There's a few more jolts still to go, but Miller and colleagues end the demo to make way for another developer in 2K's showcase hour. "This is only a portion of the full add-on content," Miller says before she disappears. "We're not speaking about any other portions today but I can tell you they encompass a wide variety of gameplay - from puzzle elements such as we're demonstrating today to the more traditional combat that BioShock is known for."

They'll also take advantage of the PS3's Trophy system, we learn subsequently, with Trophies tied into things like the speed with which you complete the levels (a timer's ever-present in the top-left). "Systems like Researching, Modifying Weapons, Hacking, and Crafting [in the single-player] are all loaded with awards," 2K Marin's Alyssa Finley told the US PlayStation Blog on Monday. "A meticulous player will find themselves up to their armpits in prizes." Writing on the Cult of Rapture website, Andrew Rudson from Digital Extremes (one of four studios contributing to the PS3 port, along with 2K Boston, Marin and Australia), had previously explained: "Each Trophy is graded based on its relative difficulty: bronze, silver and gold being the most difficult. Additionally, there is one platinum Trophy [in the game], which is automatically unlocked after you've earned every other Trophy."

The game is still unoptimised when we see it at E3, but it runs at a fair old pelt - 30 frames-per-second seems to be the norm, despite a few dips. As ever, it will take a more forensic examination post-release to get to the bottom of the 360, PC and PS3's comparative performances, but given the amount of resource being thrown at what's effectively a very late cross-platform port, you feel 2K will push as hard as possible to achieve parity.

And Miller and her colleagues are loath to stop tweaking and playing with the potential of plasmids, genes, puzzles and Rapture, even including interactive carnival games near the Ferris wheel that allow you to win additional EVE hypos, which power your plasmid usage.

It's not the most exciting feature ever, and the level we've seen is actually quite contrived, but if the devs achieve their goal of driving players to better explore the depths of BioShock's discrete mechanics and continue to evoke comparisons to Portal, they may achieve the unlikely feat of driving 2007's most controversial 10/10 shooter back into 2008's best-of lists via downloads and Trophies. Fine, we're probably being overly optimistic with that, but that happens in Rapture, and we won't be upset about having to head back there later to contemplate 2K's work on this conversion when the game comes out later this year.