December 2025 monthly summary for SuperTux/supertux focused on delivering enhanced particle visuals and solid engineering practices. Key feature delivered: Particle Fade-Out Visual Enhancement for SpriteParticle, introducing a fade-out timing mechanism and updating related objects to utilize the new feature, resulting in improved visual feedback and aesthetic quality of particle effects (notably for Walkingleaf particles). Major bugs fixed: none reported this period. Overall impact and accomplishments: elevated visual polish and player experience, with groundwork laid for future particle system improvements and lower risk of regressions due to clean, well-documented commits. Technologies/skills demonstrated: C++ graphics integration, particle system enhancement, clean Git workflow with Signed-off-by and Co-authored-by, and adherence to code style guidelines. Business value: smoother, more appealing visuals increase player satisfaction and perceived quality, contributing to longer engagement and market competitiveness.