It's been a momentous week for US developer Blizzard. On Monday the studio announced it had surpassed the eight million subscription mark for its insanely popular MMO World of Warcraft in an attempt to drum up interest in the release of what is probably the biggest game expansion ever: The Burning Crusade.

And now, after thousands queued long into the cold winter night to get their mitts on the game at midnight openings across the world, millions of Warcraft players are enjoying the new continent of Outland and embarking on the long journey to level 70.

To mark the occasion, Pro-G sat down with Jonathan LeCraft, game designer on the character class team at Blizzard, who has been working on The Burning Crusade since the World of Warcraft was released over two years ago, to get the low-down on the most anticipated expansion ever.

Pro-G: You've had a heavy involvement in The Burning Crusade. With eight million subs, how much pressure does that put on the team to satisfy the famously vocal fanbase?

Jonathan LeCraft: It puts on a lot of pressure. Sometimes we'll make a change and we have to think, "wow, this is going to affect eight million people." Sometimes it makes us think twice or three times, but in the end it doesn't really change our philosophies.

Are you one of the 8 million?

Pro-G: Are there any particular examples where you've had to think twice about a feature because of how players might react?

JL: Mainly with the big changes, like how we changed the item system. Now you have to use a rating system versus the percentage based system. We knew that was going to be a big thing, but it was necessary. Also things like the honour system, and things that we changed to make them better going forward. We have to be concerned about everybody who's used to them the way they are.

Pro-G: Was there anything left out of The Burning Crusade the team had hoped would be included?

JL: There were a few systems that we weren't able to complete that we did think were going to be good; for example the hero quest was something we wanted to put in, but we just didn't have the resources. But I can't think of anything off hand that didn't get killed pretty early that we got very far with and said no; not that we haven't done that previously, I just can't think of any Burning Crusade specifics.

Here's an example. With Hellfire Peninsula, basically the entire thing was quested and all the monsters were put down and we just ripped everything up and did it again because we weren't happy with it. And then we did that again. We got to point when we were working and we were just like, "no I don't think so." If we're not happy with something, we'll just keep iterating on it until it's good.

Pro-G: That's something Blizzard is famous for, not feeling the pressure of a release date and just saying, it will be ready when it's ready.

JL: To a degree. We don't want to ship anything until it's absolutely ready, but certainly there's a time near the end where there's still a lot of pressure. Once we've decided, we have to make sure that everything we have decided on is going to work.

Pro-G: How much of an advantage is it to be able to continue to refine the game after it has come out?

JL: It is an advantage of an MMO, in that if it's really bad or we do something that we really hate we can always change it.

How long will it take you to reach level 70?

Pro-G: There has been some criticism from high level players that TBC is trying to attract casual players, with, for example, the reduction of the 40-player raid limit and how easy it will be to get good quality items. What was the thinking behind that?

JL: All those were very conscious decisions, especially the 25-man raid limit. That was made for more than just casual appeal. We tend to be able to make better encounters for smaller groups of people just because it's a more controlled group. We can do different stuff with a smaller group.

With the better items available as quest rewards, when you first enter Hellfire (the first new area in Outland) you're going to see some of those quest items and be like "whoa where'd this come from? I can't believe this is a quest reward!" but the stuff at the end is still awesome; it'll still be worth it. You'll feel like it was worth it to go down the dungeons.

Pro-G: You don't feel there will be any hard feelings from hardcore high level raiding players who have put days upon days into getting great equipment?

JL: It depends, because when they have put in all that work some people were thinking that this is the end and whatever I get I won't ever need it again, but that all changes when we increase the level cap and that's kind of inevitable. I think dealing with that realisation will be there, but at the same time people who have raided and have tier two, they won't need new equipment until level 70, until they start doing the new dungeons. They're not going to look at the quest rewards and go, "wow, that's amazing in Hellfire," they're going to be set and definitely going to have an advantage levelling up. You will replace your gear obviously, but not until the end game.

If you've somehow managed to explore all of WoW, The Burning Crusade is the answer.

Pro-G: What is The Burning Crusade trying to achieve?

JL: More things to do really, just to expand the game. We've added a lot of content, we've got new systems, levelling up to 70. That's really been the main thing. It's just like, "hey, what can we add that's fun and cool to do and make this an even bigger world?" Changing the philosophy was only done where it was necessary.

Pro-G: What's it like internally at Blizzard now? Is it great relief that the expansion is out or is everyone still very stressed because everyone is going to be playing it and there will be a tonne of feedback to wade through?

JL: There was huge relief when we finally hit the point where we were done and had the patch that was going to go out on patch day. And then we were so excited. We got our collector's editions early and were just like "wow!" But yeah, there's going to be some big changes. There's going to be some things that we're going to have to react to and that's generally a pretty stressful time.

Pro-G: What will you be keeping a close eye on?

JL: I'm on the class team specifically, so I'll be watching all the new talents and the new abilities really closely and see how they're getting used or not used, or abused. Things which are overpowered and other stuff. Either side of the spectrum.

Pro-G: That must be one of the most pressured positions to have on the team, given that class balance is one of the things that gets the fanbase most worked up.

JL: Yeah it is! Even internally it's high pressured. Somebody comes in to our office once per hour. There's a small team of us, but each of us is always getting some attention at some point during the day.

Pro-G: One of the things some players have noticed due to its absence is new classes. What was the thinking behind that?

JL: It was just to keep the scope manageable, to keep the game manageable. It is not our intention to never add a new class, it just wasn't for this particular expansion.

Will Blizzard continue to offer the same amount of free content?

Pro-G: As class guru is there anything you can hint at about what fans can expect when the new classes do come in?

JL: If we were going to do something like that we wouldn't have even been solid on it internally yet. I've got some leanings, but our philosophy on that is that we want to add something that is just totally different and is also going to fit in well with groups, can solo well and all that.

Pro-G: What percentage of players do you expect to pick up the expansion?

JL: I would hope 90 per cent. I would love to see 100 percent, but not everyone will pick it up. 90 per cent would be pretty amazing.

Pro-G: Is this the most important expansion in videogame history?

JL: Yeah. It's huge. It's just immense. It's got all kinds of momentum. Just our midnight openings are unheard of for something like this. I would say most people at Blizzard definitely have a grasp of how mammoth and important it is. There's an amazing sense of pride. Once we finished we were just so happy that for that many people the game will be fun. It's really cool.

Pro-G: On a personal level, do you and the rest of the team play the game much?

JL: Oh yeah, hardcore! I actually have five level 60s because I'm on the class team. The sad thing is I haven't even decided which one I prefer playing. I don't want to say specifically because I don't want people to take it that I have a preference. We have people that play everything on the team. If there's anything we don't play, we have people coming into our office every day telling us what's going on in-game, whether it's something they don't like, don't think is fair or think is too good.

Pro-G: What excites you most about The Burning Crusade?

JL: I'm really looking forward to the instances. I want to get a group together and head to Hellfire right away, and especially as some of my characters aren't well equipped. For the guys who have been raiding it won't be that exciting, but for the other guys who haven't they'll just see those blue items that drop off those bosses and be like "whoa!"

Will 90% of WoW subscribers buy the expansion?

Pro-G: What has the success of World of Warcraft meant for Blizzard?

JL: It means that there are going to be some cool games coming from the studio because we are very successful. We can definitely afford to take the time and put everything we want into new games. I think they're going to even be a step above what people expect.

Pro-G: Are these games already in development?

JL: Maybe!

Pro-G: What about a console version of World of Warcraft?

JL: We don't have any plans for it specifically. We always keep all our options on the radar but we don't have any plans for the immediate future.

Pro-G: Is it to do with having to use a joypad?

JL: That's partially it. You really do need a keyboard to play WoW. I've seen some mods where people have hooked up WoW to their Wii. When I saw that I was like, well, that's got to be pretty easy to PVP against, honestly. It's not something we're looking at right now.

Pro-G: What about Diablo and StarCraft? Are they being considered at the moment?

JL: We're always considering our licenses when we think about our next product. Those are really strong well known licensees. We own them completely so we can do whatever we want. We can take the fiction in whatever direction or apply whatever gameplay we want.

Pro-G: Can Blizzard run another MMO alongside WoW?

JL: I think that we have the capacity for another one.

Pro-G: Finally, what's next for you personally?

JL: I'm going back to the States and I'm going to play a lot and start working on our next content patch as well as our next expansion.

World of Warcraft: The Burning Crusade is out now for PC and Macintosh.