In this research, the optimum decision of a multi-objective inventory game problem has been investigated under strategic complementarities in a multiplayer supply chain. The supply chain comprises a single retailer and multi-retailers under the synchronization process, the wholesale contract, and the buy-back contract policy. We apply some results in supermodular multi-objective game theory to solve these problems. The optimal decision for all players is formed in two equilibria, namely the Pareto equilibrium and the weighted Nash equilibrium. For numerical results, A genetic algorithm and dominance principle elements of the payoff matrix are used to obtain the weighted Nash equilibrium and the weighted Nash equilibrium, respectively. The analytical and numerical results using the supermodular multi-objective games concept can be significant results to solve the supply chain competition problems in the industrial engineering.