I am an experimental economics enthusiast and currently learning how to design experiments using oTree tool. Replicating top journals is an important learning method. For instance, some empirical economists learn Stata and metrics by replicating top journal codes. The same applies to experimental economics journal papers. By replicating top journals, one can become familiar with the experimental design framework and practice oTree related functionalities. The paper replicated this time is ‘Covenants before the swords: The limits to efficient cooperation in heterogeneous groups’ , published in Journal of Economic Behavior and Organization (JEBO) Volume 188, August 2021, Pages 307-321.