Greets!
I\'ve not tried out the game engine, but while editing, you can set the faces to receive lighting as follows:
Go to UV Face Select mode and search the \'Light\'-button from Editing buttons (F9) \'texture face\' tab. Click that down on all the faces you want the light to affect. Note that you can use \'Copy Drawmode\'-button to quickly assign it to all faces. Should work with any lamp.
You could try if that does it for the game engine too.