In February, Sony-owned Dutch developer Guerrilla Games' long-awaited Killzone 2 shipped for the PlayStation 3. Sony has claimed that the game was one of its fastest sellers ever. But the game, as with any long-awaited title, has not been without its controversies.

Of course, it was announced with a trailer that proved to be a target render -- something that you'll see, from the interview, still stings the developers four years later. Still, that's mostly washed away by the title's success, with an impressive 91 Metascore and positive fan response.

But even in that success, the learning process has not finished, reveals development director Arjan Brussee. In the following interview he, along with the studio's managing director Hermen Hulst, discuss the company's evolving understanding of its space in the marketplace and how development continues on the game.

In the following interview, conducted at the recent Game Developers Conference, Hulst and Brussee discuss the size and structure of the game's team -- which topped out at 190 people.

Multiplayer and single-player development and testing are contrasted, the process of patching the game is discussed, and even the rendering engine is stripped back for the world to see:

You guys finally shipped. I shouldn't say "finally". Every game is "finally", right? No matter how long or how short development is.

Hermen Hulst: It's fine. We've given birth, so we know what it feels like now.

How do you feel to have gotten through it, gotten it out?

HH: I think we're pretty ecstatic. It's great being out here at GDC. We've spoken to a lot of peers. One of them actually, earlier this morning over breakfast, said, "Well, it must feel for you guys like you've climbed a mountain and planted like a big fucking flag on top of the hill." And that's what it feels like after all those years. It's been four solid years, quite intense.

About how many people did you have on the team working behind the production?

HH: We peaked I believe for a very brief period at about 190, but much more sort of steady, we were at about 140.

Wow. That's still a huge number.

HH: It is a big team, yeah. It's a big single-player campaign and it's a big multiplayer online experience. And that was at the end. Of course, we started with about 55 people. We scaled it up over the years.

How did you structure the development of multiplayer and single-player? With Resistance, some of the content was related or repurposed, but ultimately, it was more like silos, I think. Did you take a similar approach?

HH: I think... And Arjan can tag onto that later, but I think looking back, it wouldn't have been quite healthy from a production management perspective had it been more integrated than it actually turned out to be, to be completely frank with you. We just have one game director that was technically overseeing both creations.

However, the use of the word "silos" may be a bit extreme. But they were actually two different tracks, particularly on the design side. Obviously, from a technology and an art perspective, there's a lot more integration there. That is definitely I think something that we are looking at going forward.

Arjan Brussee: I think the main difference is that with online, we started having playable in a good fashion so much earlier. I think we started three years ago with a thing that we called Friday Fragfest where we just had the whole team play through the game. At first, it was super laggy, no animations, mo-cap, etcetera, just trying out things.

That iterative approach has really, really worked well. That was in good shape real early on. I think that's required for online, so you can't really take the same approach as you do for single-player, because only at a very late moment of time, you start reaching the kind of quality that's required.

Obviously there are balance issues with multiplayer that are really important, which that really benefits. But also, is it because of content creation in a sense that single-player is waiting for assets and all kinds of things to come online?

AB: Well, they share a lot of assets, right? But I think online is getting fun real quick, even if you're in a mo-cap environment and you have a couple guys running around. It becomes really fun already, so you can test the [ideas] in a very base fashion really quickly, and really quickly iterate.

So you can see, you know -- the medic. Is it being played really well? We know -- that's a thing that we found out two years ago. We have three weeks, and every week, a different kind of medic implementation. The test is like that, to figure out what is the best way to get people involved in being a medic. And that kind of approach really worked well. You can do it really early. On that side.

HH: A single-player campaign is only fun once there are enemy types that each have their own sort of behavior, reasoning with the world. That's one of the lessons we learned from Killzone 1 -- AI needs to be a lot better. And we've spent very considerable time with a considerable amount of people on that, and I think that's what Arjan refers to do. You don't require it in multiplayer.