Lighting dissertation, Tunnel vision

Chunk

My original idea was to create a game environment form a piece of concept art but was told its not the greatest for writing a dissertation. So i changed my idea to game engine lighting, my problem now is how to make my dissertation and final game environment relevant. 

I really want to make a nice polished game environment for my portfolio, to beef it up before i head out into the world.

I need a question or topic about lighting that makes for a good dissertation that i can also use in my game environment.

I have come up with some ideas like player guided lighting, or why people choose to take certain paths, im have tunnel vision and need a new pair of eyes.

any help would be greatly appreciated.

Cheers