"When we were working on BioShock there were design decisions we made where I think I sort of lost sight of something that was important in our previous games," sighs Levine.
"It didn't really occur to me what was missing until I had an interaction with a fan at a speaking event I did. He came up to me after the event and said, 'I've got a bone to pick with you.' I asked what it was. He said, 'BioShock didn't live up to something I was expecting out of the game: none of my decisions had any permanence. None of my character-based decisions had any permanence.' I thought, 'God, yes, that's a very good point.' When I look at BioShock, I look at all the game systems, and there's a hacking system, a photography system. There's a lot of systems in it, but none of the systems really demand a player sticks to those decisions they make."
The solution? Choices with a little more kick to them. We're not talking about big narrative choices here, like who lives and who dies (it's very hard for any game to go back on those occasions without pulling off a Bobby Ewing) but we are talking about the character stuff that affects your game on a moment-to-moment basis.
"So even in a vanilla BioShock Infinite, there are permanent decisions now," says Levine. "The nostrums that are basically the gene tonics of the first BioShock, those are permanent decisions. The way these work are you can find unstable nostrums in the world, and they give you a choice between one of three powers. You make that decision right there and then and then you stick with that decision.
"The change for 1999 mode is that the decision is not only permanent: if you make certain decisions, it's now mutually exclusive of other decisions. It locks out other stuff." Levine laughs. "You choose to specialise in guns or a particular type of gun, or hacking or whatever it is, you're really going to be compromised on other things: you're not going to be able to be good at them as well. And you're going to have those times in the game where you have a limited resource of the things you're good at.