This paper examines the evolution of agent strategies in a commons dilemma using a tag interaction model. Using a tag-mediated interaction model, individual's can determine their interactions based on their tag similarity. The experimental results show the significance of agent strategies that contribute to the overall value of the commons. The paper also examines the significance of viscosity on the emergence of cooperation in the commons dilemma. Viscosity represents a specific form of openness that will be examined in the paper. An initial series of experiments demonstrates the role of tags in the n-player dilemma while subsequent experiments examine the impact of openness on the evolution of agent strategies. The paper shows the emergence of cooperation through tag-mediated interactions. Simulation results show the emergence of strategies that contribute heavily to the value of the shared commons. The role of viscosity on the population strategy set is examined and this is similar to some forms of openness in multi-agent environments.