Since my characters will have different colored eyes, and use the bge texture module to change the eyes giving them expressions, several textures would be needed. To reduce the number of eye textures needed I was considering using gray-scale textures and changing the rgb to intensity. The characters will be dynamic so I only have to model, texture, and animate two characters.
You can change the object color or the vertex color (object color must be white) of the object.
Colour2_25x.blend (266 KB)
I was using an overlay image for color and setting the underlay image as a stencil. That seems to work for what I want. Thanks for the response; I will look at it when I get home and use that method if it works better than my method I will use it.