Fault tree analysis is a useful probability theory-based tool for evaluating a system’s risk and reliability. Typically, fault trees are populated with basic event failure probabilities from a variety of quantitative and qualitative sources. This article presents a new methodology that combines simulation with game theory to populate a fault tree with strictly quantitative probability estimates for basic events in the fault tree. This new method is applied to an example ship self-defense scenario, and the probability of effectiveness against a group of small attack boats is calculated. The resulting fault tree is used to model a war gaming situation in which the players must choose optimal strategies and weapons. This articles describes a means for generating a fault tree in which the top event probability is optimized with the assignment of basic events probabilities in accordance with game theory.