Tech Interview: Crackdown 2

Actually the sky rendering in CD1 was very expensive - I'm not really sure why they initially went with such an expensive technique. Our artists also didn't like certain aspects of it and didn't have a lot of control. We replaced this on CD2 with something a bit cheaper but still very nice looking - some guys from Microsoft worked on this. It also gave our artists a lot more control over it during the day/night cycle.

First of all thanks for that video, it delighted everyone here and was like a gaming version of Koyaanisqatsi. To be honest we're wondering about why we put that much time and effort into something that takes a pretty proactive look at the game to appreciate. I do love the day/night cycle in the game, particularly now with the freak outbreaks it's become a gameplay mechanic for Crackdown but it does make things pretty hard. You've already got a hard task making environments look detailed, interesting and varied when you've got a massive, go-anywhere world.

Now add a day/night cycle and it gets even harder. You're trying to make every bit of the city look great through a massive range of lighting conditions. It's really hard. So it's great you guys managed to really show off what's great about that cycle with a time-lapse movie but I'm not 100 per cent sure we'd want to do that again!

We replaced the lighting in Crackdown 2. CD1's lighting code was fairly ad-hoc and had a lot of unusual hacks in it - the result often looked oversaturated and garish, and in fact it looked very different to what the artists were seeing in the modelling package, which they didn't like. It was also a lot more expensive than it should have been really.

For CD2 the artists wanted something a bit more normal and we also wanted to improve performance anyway. CD2 uses three directional lights (one main and two "fill" lights) for the basic lighting. It also has a hemispherical ambient term and pre-baked ambient occlusion. CD1 had pre-baked ambient occlusion too but we have improved it for CD2. The artists also have a lot of parameters they can control for the various times of day such as the colours of the lights, etc.

I think this is just because the artists chose to use the limited amount of texture memory in different areas, they could have had just as detailed texturing in the area you show - they just chose not to. They also wanted to get more detail in the middle distance, since in CD1 the middle distance can look pretty bland.

One issue with open worlds is how to manage textures – Crackdown and the sequel handle this by having a fairly large common "texture dictionary" plus a small amount of unique textures embedded into the city blocks. This can be somewhat limiting though - I would have liked to change the way texture management works and introduce a better way of streaming the textures. However, we decided that it was too risky for CD2 and we went with a solution we knew would work.

Throughout development we've tried to let the game speak for itself. That's meant a lot of in-engine screen shots and in-engine videos. Sometimes you see games promoted on the basis of CGI sequences that bear little or no resemblance to the game you get in the box. We're not keen on that bait and switch approach.

Giving away a whacking big slice of the game away for the demo is an extension of that philosophy. The core pillars of our game are the chaos and creativity you can have online through co-op play and the only way you can get that across is to let people get access to a good part of the world and its toys with the demo. So that's what we've done and can see us continuing to do in the future.

This idea actually came from our producer Roger Carpenter at Microsoft and it's a completely brilliant one. Given where the idea came from, Microsoft was 100 per cent behind it from inception. There was some extra dev effort needed to support; for one we needed a central server to keep track of all of the deferred achievements people have racked up and then activate them when they buy the final disc.

I think this is a great idea that's been working for a while on XBLA. It wouldn't surprise me to see other titles taking the same approach in the future.

We've been working with Proper for a while now, several of their coders helped get the game completed before moving onto PDLC. Like Crackdown 1 we're aiming to give players a nice big juicy and meaningful PDLC package rather than just a few extra bits of pretty meaningless digital bling so getting Proper on board to help has been really useful. We also needed to get development underway before CD2 was complete which also lead us down this route. Right now that seems to be working really well.

Download the demo and play co-op with some friends. It's absolutely the funnest thing ever. We've tried really hard but you just can't take a screenshot of fun so you really need to experience it yourself.