PlayStation games lit their worlds mostly by hand. Colours were baked into vertices and textures, and the mood of a stage came from careful palette choices rather than a lighting engine.
Keep the mood, change the model
The renderer reads each scene's original lighting intent, including sun direction, time of day and colour, and uses it to drive a modern lighting model. A dusk stage stays a dusk stage. The difference is that light now behaves consistently across every surface.
Shadows, reflections and ambient occlusion
With a real light source, aircraft and buildings cast shadows that ground them in the world. Wet runways and the sea reflect the sky. Ambient occlusion adds the small contact shadows that give objects weight.
Ray-traced effects are in active development and will arrive as an option for hardware that supports them.
Always optional
None of this replaces the original. The Original presentation keeps the hand-tuned look exactly as it shipped, and you can switch between styles at any time. See the rendering overview for side-by-side comparisons.