The Holy Britannian Empire covers a third of the globe. Lelouch is a privileged young Britannian growing up in Area 11 (formerly Japan), but Lelouch has a deep grudge against the Empire. A strange girl grants him a supernatural power: the ability, given a moment’s eye contact, to make a person do anything he wants. With this secret weapon, Lelouch embarks on a campaign to free Japan and destroy the Empire.
The most obvious parallel when watching this is with Death Note. Lelouch works from the shadows, keeping his identity secret and using the alias Zero to gather an organisation of followers, and his brilliant strategies – and judicious use of his hidden power – enable seemingly impossible victories. But he’s also insanely arrogant, treating humans on both sides like pawns, seeing every event in terms of how it affects his plans.
So it’s oddly reminiscent of something very good. Is that a bad thing? Not necessarily. Where Code Geass departs most is in scale. A bigger cast of characters are invovled, both in Lelouch’s own life and on both sides of the war. Battles don’t stay neatly psychological and behind closed doors, they spill out onto the streets, with the lives of thousands in the balance. Lelouch turns the quiet resentment of the oppressed Japanese people into a war.
His main rival is Suzaku, his oldest friend and a Japanese who has been promoted to an honorary Britannian for his military service. He’s deeply principled, believing in changing the system from within by standing as a visible example of how the two races can work together. He’s deeply opposed to Zero’s campaign, stating that any victory achieved through evil means must be hollow. In their daily lives Suzaku and Lelouch are close friends; meanwhile Suzaku is the pilot of a mech that is the biggest thorn in Zero’s plans.
Yes, there are mecha. They take part in most of the battles, but aren’t really the focus. They serve mainly to limit Lelouch’s power by preventing eye contact, and to help preserve his and Suzaku’s identity. They’re also a good modern-era version of the military advantage that built the empires of the 19th century: in a world where everybody has tanks and helicopters, mecha are the only weapon that’s overwhelmingly more powerful. They’re fast, agile, precise and heavily armoured. In the hands of a skilled pilot, a mech can take down a small army of conventional armaments.
There are really no clear good guys in this series. Britannia are mostly oppressive elitists, who want nothing more than to bully other peoples into submission. Despite his brilliance and his reasons, Lelouch does many things that are not just questionable but downright horrific. Suzaku is well meaning but his principles are unrealistic, and attempting to follow them leads to suffering.
What Code Geass best at is shock. There are no long stalemates, no time to catch your breath. No situation is stable for long, and everything fragile can break. Change is constant through the series, and the finale is truly shocking.