Worked on the YoYoGames/GameMaker-HTML5 repository to enhance visual customization for game development by implementing new JavaScript functions that allow per-sequence alpha and blend control for layer sequences in the HTML5 runtime. Designed and delivered APIs that align with existing layer_sequence_x behavior, ensuring a consistent experience for developers working with visual layers. The work focused on expanding the flexibility of game artistry by enabling developers to set alpha transparency and blend modes for individual layer sequences. This feature was implemented through careful function design and integration, leveraging JavaScript and game development expertise to address issue #14404 and improve runtime capabilities.