Developed and integrated a new playable faction, YZY, for the hoi4-modding-den/Dens-HRE repository, expanding player choice and immersion within the Hearts of Iron IV modding ecosystem. The work involved creating assets, defining localization, establishing historical starting conditions, and configuring a new leader, all implemented using Paradox Script and yml. Integration required updates to game state and unit history files to ensure persistence and a coherent player experience. The developer focused on configuration and game modding workflows, enhancing the asset pipeline and localization coverage to support future content. No major bugs were reported, reflecting careful attention to integration and testing.