DUAL REALITIES:
This is a tough game. Really tough. Just to pull this game off requires a hefty sense of focus not only on another performer and his/her sense of "where," but also on your own individual sense of "where."
Two performers can play this game. The audience will give each performer a "where" and some kind of action to do in that place (i.e., shopping, dancing, washing dishes, coloring, etc.).
Each actor will then start building that "where" seperately, with the eventual goal of interacting with the other performer. The point is not to "merge" the two realities, but simply to have them intersect one another and see what happens. Yes, it is a lot like dating in the '90s.