heart The series is set in a reality where Japan is taken over by the "Britannian Empire" with their powerful new robot weapons, the Knightmare Frames (which are the robots you see)
ninja Britannia stripped Japan and its citizens of all rights and freedoms and renamed the country "Area 11."
3nodding The main character Lelouch is a Britannian prince who was disowned by his father, Emperor of Britannia, after his mother was murdered. He has vowed to destroy his father and Britannia as revenge.
redface He gains an ability through the mysterious power of the "Geass" through C.C. (the green haired girl) and he becomes the leader of a resistance movement called "The Black Nights" to fulfill his two wishes: to seek revenge for his mother and to construct a world in which his beloved sister Nunnally can live happily.
cheese_whine Its not just about robots. (Information from
http://en.wikipedia.org/wiki/Code_Geass I didnt think of all this on my own)