Worked on the rathena/rathena repository to address a gameplay issue related to hat effect application in a game development context. Focused on improving the hateffect script by implementing a guard that ensures hat effects are only applied when not already present, which prevents unintended repeated applications and enhances overall reliability for players. Utilized C++ and scripting skills to identify and resolve a critical edge-case bug, thereby reducing the potential for player-visible issues and contributing to code quality. The work demonstrated attention to detail in maintaining gameplay consistency and release readiness, with a targeted fix that closed a notable reliability gap.