Kinetic Interaction Software System (KISS)
The Software Architectural Design Document mentions quaternions.
is a system designed to animate the realistic dynamic reactions of
an avatar to its 3D polygon environment. This involves the complete
system from 3D polygon environment creation, to key framed animation
creation, to allowing users to input environment and animation
manipulation commands, and finally to displaying the effects of these
commands: in terms of creating Inverse Kinematic animations from key
frames, polygon collisions detection, and computing and displaying
realistic dynamic simulation reactions.