1. Implement the RenderingEngine class and rendering pipeline
2. Create a Theme system and refactor visual styles
3. Implement draw methods for game entities
4. Separate UI rendering
5. Optimize rendering (this can be an ongoing process)

We have already implemented point 1 and 2 and 3, i.e. implementing the RenderingEngine class and rendering pipeline, and creating a theme system, refactoring visual styles, and implementing a Drawable interface for game entities.