If you ever wondered whether Irrational Games could do anything BioShock-related without throwing in a twist, I've got news for you: they can't. On Monday afternoon I went to a press event in Boston expecting to see a preview version of the first BioShock Infinite DLC pack. Instead I was told the DLC, called Clash in the Clouds, was finished and due out a day later. I got to play through the entire thing. It's pretty good, making more fun out of Infinite's varied combat.

But that wasn't even the main surprise. The biggest twist of the day was the news - accompanied by a trailer and a chance to interview creative director Ken Levine - that BioShock Infinite will be taking us back to Rapture, potentially later this year, where players will get to control Booker DeWitt and Elizabeth, each of whom gets their own playable instalment in a two-part detective story called Burial at Sea. If that's not enough excitement, Burial at Sea is set on New Year's Eve, 1958 - one year before the fall of Rapture. So we get to see it in its pomp.

You get the idea.

I sat down with Levine about half an hour after the announcement to find out how it came about, what we can expect, and why Irrational chose to tell a new story rather than pick up one of the threads left dangling by BioShock Infinite.

Eurogamer: Let's talk about Burial at Sea, because that's the curve ball today. What can you say about it at this stage? What's the premise and where are you going with it?

Ken Levine: At the very beginning, you're Booker, private detective in Rapture, in your office and this woman comes in, and you two don't seem to know each other, and we don't explain that. We always like to put people in a place where there's a story that ends up making sense, but we don't want the obvious... We like people immediately having a sense of wondering what's going on.

Eurogamer: Sort of displaced and confused a little bit.

Ken Levine: Yep, and it all will make sense eventually. The story takes place on New Year's Eve, 1958, which is the night that the bombing happened in the original Rapture and the revolution started, and we were really excited, having done all the work on the population - a living, breathing population in Columbia - because Rapture was a tomb, y'know? Originally we wanted to show Rapture when it was fully alive, but do it in the context of an interesting story, not just to go back and talk about Midi-chlorians, you know? To do it in a sort of integrated way, but to tell a story we thought was important to tell with these characters as well.

Eurogamer: So you've got quite a few little goals going on there all at once.

Ken Levine: Yeah. For DLC it's pretty ambitious, I think.

Eurogamer: It's your usual layered approach, but in a new context, I guess.

Ken Levine: From a resource and work standpoint, it's effectively like making a small part of a new game. Almost all the Rapture elements are newly created for the engine. The city outside you saw is actually a 3D structure, whereas in the original game it's 2D images. I think every single environment is created from scratch. There's maybe a few objects we brought over, but really everything is new.

Eurogamer: So you're playing as Booker, you start off with Elizabeth coming into this office...

Ken Levine: A classic noir. A woman comes into your office and offers you a job. And she's got the femme fatale kind of look, and you two don't seem to know each other, or you don't seem to know her, and...

Eurogamer: And she presumably tells you about some problem she's having.

Ken Levine: Yes, and related to a problem you have. Like all story things, I'm going to be sort of vague about things, but the experience takes you both through a part of Rapture that's pristine and you'll meet some characters... You know, this is about a year before the events of BioShock 1, and so you'll meet some characters before they've gone as deeply crazy as they have [in BioShock]. Some fan favourites, but they're not just cameos - they're deeply integrated into the story. And then there's a...

Eurogamer: Can you be specific at all?

Ken Levine: I'd rather surprise people. I think people won't be disappointed.

And then there's a fair amount of the action takes place in... After Fontaine's business was taken over by Ryan, he had to put all of Fontaine's people somewhere. A lot of the action takes place in an old department store - a Fontaine department store - that's been sucked to the bottom of the ocean. They're all sort of put in there as basically a sort of Alcatraz. So part of the action takes place in a very traditional BioShock 1 kind of feeling with lots of splicers and broken, screwed-up stuff, and part of it takes place in a very pristine Rapture, so you really get to see both of those experiences.

Eurogamer: What kind of gameplay implications are there? What's coming in from Infinite, from BioShock? What's new?

Ken Levine: So, it is built upon Infinite, but we have made a lot of changes, and the amount of changes to style of gameplay vary from when you're Booker in the second one [Clash in the Clouds being the first DLC pack] to Elizabeth in the third one. It's more stylistically and gameplay tuned like BioShock 1. Infinite generally had a lot of big, epic-scale encounters, where BioShock 1 was more about you observing splicers in their natural habitat and being able to set up combat a little more, so we've really pushed back toward that a lot.

Eurogamer: Are you bringing the Big Daddies back?

Ken Levine: I think people would be pretty unhappy if there were no Big Daddies. I won't say exactly how, but yes, they are involved in a certain way, and the combat will probably feel more like BioShock 1 combat, but there's a new weapon and a new vigor plasmid in each of the DLCs. Well, let me think - I don't want to talk too much about the third one, but certainly for the second one there's a new weapon and vigor plasmid. I think we really tried to modify the gameplay so it felt more like a Rapture experience.

Eurogamer: Are you going to try to rationalise it with the events of Infinite, or is it considered a completely separate episode, splinter, whatever?

Ken Levine: I think it's safe to say we will integrate everything.

Eurogamer: You mentioned that you didn't want to just go back to the cutting room floor, but why not?

Ken Levine: You're sort of in a damned-if-you-do, damned-if-you-don't situation, but at the end of the day you just have to do what you think is the right thing to do. And for us, we had the opportunity to... The idea for this, we had the idea for this, and we knew it was going to be way more expensive and way more complicated, because instead of just taking all the assets from Infinite and never even modifying them, we have to do a whole bunch of work, you know?

But it was so appealing to us that... The story idea was so appealing that we really wanted to do it, but we knew it was going to take time, and we knew people were going to get impatient and frustrated, but at the end of the day you have to kind of do what you think is going to be right for them in the long run. At the end of the day, people got mad when the game was delayed, but if we released it when it wasn't ready, it wouldn't have served anybody.

So you have to sort of take your lumps there, and this one is sort of frustrating because gamers want it to be new, but they don't realise it takes real time, and it's been tough, because people haven't really got... I haven't really been on much of a vacation since, and it's stressful, but you want to balance between getting something great - well, you never know if something's going to be great, but you want to give it the chance to be great - and something timely. So Clash in the Clouds is sort of a compromise between timeliness and scale.

Eurogamer: Yeah, my first thought was it sounds cool but it's probably a stopgap to give you some cover to do this.

Ken Levine: Yeah, it's $5, and there are people who really like the combat. I think for $5 it's a really good value. It's not as ambitious as the other two - I don't think we're pretending that it is - but that's also why we want to say it's out tomorrow [30th July]. Here it is, it's $5, it's out tomorrow, we're not going to have this huge build-up to it - it's just fun, go play it.

Elizabeth's new femme fatale look.

Eurogamer: Before I came out here, everyone who was allowed to know I was coming out here was saying, ooh, I wonder what they'll do - will it be Saltonstall or Preston Downs or more of the Luteces or whatever. You weren't tempted to go back and do things there? You must have had content that had come quite a long way.

Ken Levine: You know, here's actually what happens, Tom. There's content that... And this is sort of the tragedy. You know the term unintended consequences? People feel so passionately about stuff on the cutting room floor, that even stuff we legitimately cut from Infinite just because it wasn't working or it evolved and we didn't want that, but it would have fit in well in Clash in the Clouds, we have to be careful of putting it in, because then people would say we did it to hold it back.

So in fact there's stuff that's not in there that we could have put in there, because of this particular notion, and I think you're seeing that people get so... There's so little trust towards the developer that you sometimes have to just say, well, you leave that permanently somewhere. It's a shame, because there could have been maybe a couple of characters they hadn't seen before, but they were technically done before, so we have to be careful we don't do any of that.

Eurogamer: It's interesting, because you don't strike me as someone who's intimidated or scared of abuse on the internet...

Ken Levine: It's not that. It becomes a distraction, and then you end up... The conversation becomes so much about that that you run out of space to talk about the actual thing. And, so no, listen, trust me, the amount of s*** I get over how long this is taking? But that, for me, I will take that forever, because I'm like, I'm going to make it better, and I know when people, when we show it to people, people are going to have a smile on their face. If you like BioShock, I can't see how you couldn't.

Me, when I saw... We worked a lot on that scene [in the Burial at Sea trailer]. The first street you see when you come out of Booker's office in the beginning, when I saw that street finally done, I had a huge smile. You know, the whale going on outside and all of that stuff. How can you not? When I saw... When we finally got Elizabeth in her femme fatale look, and working on that. I had a huge smile on my face, so I know that.

But there are fights I'm willing to have for something that's a huge amount of value, and I know at the end of the day will be positive. But no, look, trust me, you can't be in the position I'm in and be worried about your feelings. It's about how much time gets diverted from the actual product, and that's why I care about it, because I want people focusing on the things that are actually interesting.

Eurogamer: Will the DLC be out by the time the next-gen consoles are out?

Ken Levine: I'm not going to say any dates until we're absolutely positive. I imagine some of it will slip past the... At least some of it will slip past the... First one won't.