Shattered planet was a tough world to work on and design. The planet was simply falling apart around you, the challenge was creating a visually interesting area while maintaining a navigable play space. I worked on all of the rocks for this planet with Mark Skelton. They were extremely fun to sculpt due to their slightly stylized and exaggerated forms. We needed large forms with areas of detail. We also used detail normal maps for extra scale and detail. Here you see the macro sculpts from ZBrush.
Here is a shot from one of the later levels in the middle of a battle. Chris Smith did all of the vehicles on Starhawk, and he killed it!