This paper describes an interactive software environment designed as a social interaction simulator with embedded comprehensive recording and flexible assessment facilities. Using schematized visual sketches similar to cross-cultural facial universals (Ekman, 1999), Mimics (Shmelyov & Aidman, 1997) employs a computer-game-like scenario that requires the subject to identify with an avatar and navigate it through a playing field inhabited by hosts who display a range of facial expressions. From these expressions (which are highly consequential), the player has to anticipate the hosts' reactions to the avatar (which may vary from friendly to obstructing or aggressive) and choose between negotiating with a host (by altering the avatar's facial expression), attacking it, or searching for an escape route. Comprehensive recording of player moves and interactions has enabled computation of several fine-grained indices of interactive behavior, such as aggressive response styles, efficiency and motivation in conflict/cooperation contexts. Initial validation data and potential applications of the method in the assessment of personality and social behavior are discussed.