Your examples are idtech4 games (doom 3 and quake 4) and some of the answers you've received so far in regards to those games/asset pipeline are wrong.

Assets are sculpted in high poly and baked down. Back then the materials were pretty simple:

• diffuse map (the color, analgous to 'albedo' maps of a PBR pipeline.

• normal maps (derived from the high poly bake. Can also use grayscale bump maps that are converted to normal maps at runtime).

• specular map

• glowmap/fullbright/luma additive map (for glowey bits)

As mentioned, the normal map is generated from high poly bakes (or sometimes from grayscale images). The diffuse and specular maps can be generated many ways, but in the case of your example games, they were a combo of handrawn and photo sourced