How Was This Made?

I hope this is the right category.
so i've come across this video on youtube

and just saying this is impressive, but unfortunately this was 12 years ago, so i can't ask the creator how he did this, so im asking if anyone knows how this was made? and just to clarify im talking about the lighting

this lighting can be achieved easily with dx7 lights, or with vertices colors, but your surfaces (meshes) must be subdivided enough so that the lighting shading is spread uniformly.

a good subdivision of surfaces (meshes) is 0.5, which means that, for a wall or a floor or a ceiling or a door, you must have a vertex each 0.5unit or less.

the flickering effect is either a variation of the light color, or of the vertices colors...

see these examples :

lighting shading with dx7 light or with lightmesh() :
https://archive.blitzcoder.org/forums/code-3d-effects/3201.html

custom lighting shading with vertices colors :
https://www.blitzcoder.org/forum/topic.php?id=1396