I think it is good idea to make a relative complex but compatible glsl material for BGE.
I think this example is good enough: useable for good looking materials and simple. For example I use only similar materials in my game:Dead Cyborg.
Please test this material (see .blend below) on your machine and make reports in this topic:
-your operating system
-send screenshot and infos if you have problems with this example material!
Result: check the attached image!
So the material:
-one UV (sorry, I have problems with multiple UVs with some ATI and with some integrated videocards)
-one color map multiplied by vertex color
-one normap map with alpha channel for specular and stencil
-a fake reflection/fresnel texture (angular map) that masked by the stencil (normal map alpha)
Very-very important, the lights - you must know the lights are compiled into the shader:
-one spot with shadow and with specular
-one spot with shadow but without specular
-4 other lamps without specular
You must know: specular is slow down the glsl render and makes very complex shader, so I always use that fake reflection/fresnel texture. So we have only one specular lamp.
And the blend (my very old horse model): http://etyekfilm.hu/good_glslmaterial_that_compatible.blend