Socially Relevant Simulation Games (SRSG), a new medium for social interaction, based on real-world skills and skill development, creates a single gaming framework that connects both serious and casual players. Through a detailed case study this paper presents a design process and framework for SRSG, in the context of mixed-reality golf swing simulations. The SRSG, entitled "World of Golf", utilizes a realtime expert system to capture, analyze, and evaluate golf swing metrics. The game combines swing data with players'backgrounds, e.g., handicaps, to form individual profiles. These profiles are then used to implement a golf simulation game using artificially controlled agents who inherit the skill levels of their corresponding human users. The simulation and assessment modules provide the serious player with tools to build golf skills while allowing casual players to engage within a simulated social world. A framework that incorporates simulated golf competitions among these social agents is presented and validated by comparing the usage statistics of 10 PGA Golf Management (PGM) students with 10 non-professional students.