Alex and I were thinking of doing something related to manipulating noise/particles in a 3D space. Some sort of noise (perlin noise?) would drift randomly in the space, and when the user steps into the scene, the noise will interact with the user in some sort of way. The user can also use gestures to interact with the noise to control it. The manipulation could be similar to how the jedi manipulate the force in star wars.
It would be interesting to observe two people “duking it out” in our application by throwing and manipulating the particles around them.