Contributed foundational gameplay systems to the pacalso-jjc/2425-2nd-cc3-1b-rpg repository by developing a Merchant trading system and a Material data model for crafting. Leveraging Java and object-oriented programming, implemented the Merchant class with stock management and transaction scaffolding to support in-game trading, while the Material class introduced structured methods for defining crafting materials and their properties. Maintained thorough documentation using Markdown, ensuring class diagrams and codebase remained aligned as new features were integrated. The work emphasized scalable data modeling and consistent documentation practices, laying groundwork for future business rule iteration and data-driven gameplay enhancements without introducing bug fixes.