Metagame analysis is a process of resolving a conflict problem, by focusing on finding a stable state common to all persons or firms involved in this conflict. This paper aims to valuate the roles of a third party in the conflict, and examine robustness of outcomes of the metagame analysis. In this paper, an actual conflict concerned with the urban development is analyzed with metagame, and thus the final equilibrium results are obtained by using an improved algorithm. The obtained results are compared between a two-person-game and a three-person-game, and the sensitivity of the equilibria related the change of players' criteria is discussed in detail.
