When we spoke to Dax Ginn (marketing game manager at Rocksteady) earlier this year, he made it sound like you started work on Batman: Arkham City before Batman: Arkham Asylum was finished. Were the games developed in tandem?

No, we didn't develop anything in tandem! We really were kicking ideas around at that time – we certainly hadn't started development. As a studio we tend to focus on one thing at a time so everyone was focused on finishing Arkham Asylum.

Once that was done, we started thinking about where we could go next. Arkham City was a rough idea for what we wanted. We did a couple of concept drawings for it – which you can actually find in the game – but that was far as we got with it before Arkham Asylum was done. (Laughs) We're not smart enough to develop two games of that size at the same time!

Dax also said that the game was driven by technical considerations. Did that extend to some of Batman's gadgets and capabilities? Did you have ideas you had to shelve and then wait to put them in this game?

There's never really any concept of waiting, to be honest. We started Arkham City with a blank slate, really, mainly because we believe passionately that we have to make the best game we can possibly make. That's what we do with all our resources. If we come up with a good idea that we want to see in the game, we put it in the game, unless it's literally five minutes before release. I'm trying to squeeze in every idea I possibly can way after the production team says, 'Right! This has to stop!'.

There's no concept of holding any ideas back. I just feel like it's so rare you get the chance to release a game which has this level of anticipation swirling around it. We need to make the best game we could possibly make – then we'll worry about what comes next.

With that in mind, were there any ideas that landed on the cutting room floor with Arkham City?

There weren't actually. What tends to happen is that we come up with some ideas, try them out and then they kind of morph into other things. We'll try something out, decide it wasn't very good, but that we liked a bit of it … our process is very iterative. There's nothing really that just drops into our game fully formed. It might be that we change the effect of a device or a mechanic, but there's nothing we throw out completely.

Batman: Arkham City

One of the game's strongest aspect is the story, which was penned by (Batman Animated Series writer) Paul Dini, but I imagine you had some idea of where you wanted Arkham City's plot to go before he got involved. Without getting too spoilerific, there are some pretty major developments in the game's story…

[Laughs] Indeed!

How many of these developments were set in stone from the beginning? Did you, for example, know how you wanted the plot to end?

We did know right at the start. Paul Dini flew over right at the start of the development with a guy from DC we work very closely with, and all of us kicked around ideas. We knew exactly where we wanted it to go – without getting into spoilers – right up to the end.

We knew the major plot points, and as the game developed we filled out the journey there. So we started the game knowing five or six main beats, but the rest is down to the development process. There's a lot of stuff in the game, which, if you play it through a second time, will make more sense the second time you play it.

Part of the fun of doing a Batman game has to be using his villains…

It certainly is!

How did the hierarchy of the villains come about? Did you know exactly which villains you wanted it and how they all slotted into the plots and subplots? Did some villains start off as main protagonists and then have their roles diminished?

It tended to happen more the other way round (laughs). We tended to have a villain have a walk-on part and then we'd decide, 'Hey we really like this character, let's give them more to do!'. Once the characters were in the game, we could then use them and fulfil their potential in the story a bit more.

We knew we wanted the Joker in right from the start, for obvious reasons. We also wanted Two-Face and The Penguin, because they're both big iconic Batman characters, and we also needed two characters the players would believe would be battling for control of the streets. Out of all of Batman's villains, those two have the most clout.

Batman: Arkham City

Hugo Strange came relatively early on as well. It was one of those questions we had of, 'Who do we want running the prison and who would present a more interesting challenge to Batman?' We quite liked the idea of having a character who knew who Batman was and could threaten him in a completely different way.

The Riddler in this game looms larger than in the last game and many of the puzzles guarding his trophies are fiendishly hard to crack. Was that your intent from the beginning? To punish the player in this way?

(Laughs) Not so much about the punishing thing – I agreed with everything up until them. No, but the last game was more a trophy collecting game where you only had to be aware of your environment and investigate it a bit more.

We really wanted to up the Riddler's game in this one, which made sense in terms of the game and the plot. The Riddler is furious with Batman for humiliating him in Arkham Asylum, so in this game he really pulls out the stops to beat him. It wasn't meant to be punishing … but challenging, intellectually stimulating, yes. You also get to prove you're better than Riddler. Like you mentioned earlier with the rogue's gallery – they're all so different and all have different motivations – so it was great to tap into that. Riddler's number one motivation is proving how much smarter he is than Batman.

We spent about three weeks coming up with the trophy locations and trophies and challenges and riddles for Arkham City. It was a lot of fun.

Batman: Arkham City

I imagine the beta-testing for the Riddler content was pretty exhaustive?

The testing was … well there was a lot of it. It's an open world game so you can go anywhere and it's easy to break the logic on a lot of stuff. We're really committed to putting out very high quality and really polished experiences. We'd never want release anything that had a ton of bugs in it.

I think the nice thing about the trophies is that it's an optional extra and you can do them when you want. You not locked into doing them and you can take your time. And as you uncover more and more of them you can unlock the Riddler rooms which are some of my favourite stages in the entire game.

How did the other playable characters come about? Was it always the idea to have Robin and Catwoman available for the player to use?

Playable Catwoman came very early on because we wanted a playable character who was a very nice counter to Batman – someone who wasn't as morally rigid. Catwoman provides that, she's far more… flexible than Batman. Morally, I mean. She also has an interesting relationship with him as well, so we could bounce them off each other.

We aso talked about Robin and what we could have as DLC [downloadable content] – but that conversation came much later.

Batman: Arkham City

Speaking of DLC, what can we expect for Batman: Arkham City in the coming months?

The main thing we're doing is the challenges for Robin and we're doing some avatar skins as well …

Any story-based DLC?

[Smiles] I don't think I'm allowed to talk about that at this stage.

Arkham City is huge and I've heard a rumour that this is the last open world game Rocksteady are doing because it was such a huge undertaking? Is that true?

Who is spreading that rumour? (laughs) No, that isn't the case at all!

When we started the game we didn't sit down and say 'Let's make an open world game'. We looked at what we be a fun game to make and a fun game to play. That's what drove the open world decision. If we felt there was a story that was worth telling for a character that didn't involve an open world, we'd do that. It's more about what we think is a good fit, what will be fun and what gets the team inspired, rather than picking a genre for the sake of it.

It was an awful lot of work - no doubt about that – there was a lot of late nights and a lot of weekend working, but we think it was all worth it. So that would never put us off a similar experience in the future.

Did you ever worry that you were cramming a bit too much into the game?

Ah … er … the scheduler said that! (laughs) I worry all the time – I guess that's what I'm paid to do. I just felt that it was the most exciting thing we could do at the time and the team were really driven to do it. We wanted to make the best Batman game of all time. That was the end game.