Surfing the net, I came across Chris Hecker’s website.  He is one of the developers on the Spore team and his work “centers around using proceduralism to enhance player creativity and agency”. 

He wrote an 11 page draft paper on the Spore procedural animation system.  According to his page,  it gives a reasonable overview of both the authoring system, using our custom OpenGL animation tool Spasm, and runtime playback system.

Character animation in video games—whether manually key-framed or motion captured—has traditionally relied on codifying skeletons early in a game’s development, and creating animations rigidly tied to these fixed skeleton morphologies. This paper introduces a novel system for animating characters whose morphologies are unknown at the time the animation is created. Our authoring tool allows animators to describe motion using familiar posing and key-framing methods. The system records the data in a morphology-independent form, preserving both the animation’s structural relationships and its stylistic information. At runtime, the generalized data are applied to specific characters to yield pose goals that are supplied to a robust and efficient inverse kinematics solver. This system allows us to animate characters with highly varying skeleton morphologies that did not exist when the animation was authored, and, indeed, may be radically different than anything the original animator envisioned.

Visit this link to download the Spore Procedural Animation System paper

Oh, you can also catch an MP3 of an interview he did over at