Within this project we aim to develop an extendable core-EGSE around a HW/SW co-simulator based on ESA’s SIMULUS and EGS-CC for rapid integration and testing of advanced solutions, aiming to lower the space market entry barrier for SMEs and universities. The system shall act as a miniaturized satellite development testbed, leveraging EGS-CC’s concepts and data interfaces. The SIMULUS software shall be tailored and striped to the needed core functionality for a closed loop simulator, to facilitate its handling and increase its robustness. The system shall leverage existing open and standardized interfaces like SMP2 and ECSS-SMP. It shall serve as minimum and core EGSE, representing a cost-effective, reusable, and extendible rapid development platform for smallSat missions. Universities and SMEs shall be able to grow their own facilities around the EGS-CC core. Especially the usage of COTS HW demands capabilities to assess onboard anomalies as well as the effect of mitigating actions in a realistic mission setup on ground. The simulator enables developers, maintainers, and operators to validate their design, their maintenance change and their operational procedures. Making it a versatile mission end-to-end verification and validation tool. Within this project the system concept and core-prototype shall be developed and established in HW and SW. There are open discussions about an evaluation of the simulator against an Engineering Model of DLR’s distributed high-performance OBC (ScOSA), which is scheduled for flight on the DLR compact satellite mission.