thanks!
I’m not sure what you mean about Godot’s “meager rendering options”, I don’t see any limits. I wrote a custom raymarching shader (see link below for resources), and slapped it on a quad in front of the camera (super hacky, I know). and yes, the shadows are raymarched too! the only things that are not raymarched: text, menus, screen fade effect, and skybox (the raymarching shader distance-fades alpha to reveal a standard ProceduralSkyMaterial).
if you want details about how to implement a raymarching shader, I suggest Inigo Quilez’s articles — it’s a real treasure trove!