With the properties of autonomy, social ability, reactivity and pro-activeness, agents can be used to represent entities in distributed simulations, where fast and accurate decision making is a determining factor of the whole environment. Resolving concurrent interactions is a key problem of this kind of system, as the shared environment needs to allow agents to interact with the environment in a causally consistent way. There will usually be either mutually exclusive or collaborative interactions. This paper presents our research in designing a middleware component called Interaction Resolver (IR) to resolve the effect of concurrent interactions and still guarantee the consistency and causality of the system. The ownership management services provided by the High Level Architecture (HLA) are compared with IRs in resolving mutually exclusive interactions in our prototype, a minesweeping game. Conclusions are drawn based on the experimental results.