I would like to create a hologram of sci-fi ship. I created materials in blender render and hoped, that they will be easily used in game engine too (my mistake).
The trick: Set the object to 'shade smooth' and use the surface normal. It doesn't work everywhere (such as the left edge of the object, but it works well enough in a lot of cases. I use this trick quite often, for things like fire, which you can do with a single distorted sphere and some UV-scroll.
Note that this requires GLSL, and uses a node material.
The blend for the cloud can be downloaded from blenderartists