This collection of excellent papers cultivates a new perspective on agent-based social system sciences, gaming simulation, and their hybridization. Most of the papers included here were presented in the special session titled Agent-Based Modeling Meets Gaming Simulation at ISAGA2003, the 34th annual conference of the International Simulation and Gaming Association (ISAGA) at Kazusa Akademia Park in Kisarazu, Chiba, Japan, August 25–29, 2003. This post-proceedings was supported by the twenty-first century COE (Centers of Excellence) program Creation of Agent-Based Social Systems Sciences (ABSSS), established at the Tokyo Institute of Technology in 2004. The present volume comprises papers submitted to the special session of ISAGA2003 and provides a good example of the diverse scope and standard of research achieved in simulation and gaming today. The theme of the special session at ISAGA2003 was Agent-Based Modeling Meets Gaming Simulation. Nowadays, agent-based simulation is becoming very popular for modeling and solving complex social phenomena. It is also used to arrive at practical solutions to social problems. At the same time, however, the validity of simulation does not exist in the magnificence of the model. R. Axelrod stresses the simplicity of the agent-based simulation model through the “Keep it simple, stupid” (KISS) principle: As an ideal, simple modeling is essential.