This book describes the development of an intrusion detection system for online poker, which uses player's game strategy as the behavioral profile. The system is improved by modifications to the similarity measure functions and different ways of representing behavioral signatures. The system is further enhanced by inclusion of spatial, temporal and contextual information about the environment alongside the user's behavior. Possibility of creation of artificial behavioral profiles and use of such profiles for spoofing of behavior-based security systems is investigated and promising results are achieved. In a somewhat related research, recognizing importance of games in our experiments, it is proven that poker is a game of skill. Finally, a number of games are analyzed in terms of their spatial ontologies.