I tried to have an texture that control the transparency of a face but it doesn’t work like it does with Blender Internal rendering.
I have a simple place with a blend sphere texture set to “spherical”. Black color in multiply mode. Alpha button is checked with value at 1. It does the transparency on the edge of the object when I press F12 but in the Game Engine, my plane is still solid, even when I check GLSL shading.
As you said, you must first be in GLSL shading.
Do not check Alpha down, as that is not what controls transparency. I’ve seen a lot of confusion in this before, but transparency is controlled by the Transparency option in the Materials tab, not the Textures tab. If you have an alpha mapped texture, then you can check the Alpha option, but it is otherwise useless. Checking it down will remove the alpha effect from an alpha mapped texture.