The red corridor (Shader)

Procedural generated in a fragment (pixel) shader.

The cracks were made by combining a built-in texture in Shadertoy with some blend operations.
The wall uses a built-in brick texture. To make it look like a burnt wall, I used burn blend and a negation blend.

* Procedural generated in runtime
* Ray Marching and SDF (signed distance field)
* Menger Sponge fractal
* Soft shadows
* Ambient occlusion

Shader Language: WebGL