We propose GODS, an ecosystem for the evaluation and study of world-wide distributed and dynamic systems under a realistic emulated network environment. GODS allows the evaluation of a system's actual implementation in reproducible experiments, collecting global knowledge about the system state. Furthermore, GODS addresses the problems of debugging distributed algorithms, performance tuning, measuring bandwidth consumption, regression testing, and benchmarking similar systems, thus offering a complete evaluation environment for distributed applications. Our framework uses ModelNet for the network emulation and enhances that by (1) adding dynamism by varying link properties, partitioning the network and emulating churn, (2) offering global knowledge about the observed system by gathering statistics and events and (3) enabling the user to easily deploy, manage and monitor complex, large-scale distributed systems.