The Empire of Brittania has invaded Japan using giant robot weapons called Knightmare Frames. Japan is now referred to as Area 11, and its people the 11s. A Brittanian who was living in Japan at the time, Lelouch, vowed to his Japanese friend Suzaku that he'd destroy Brittania. Years later, Lelouch is in high school, but regularly skips out of school to go play chess and gamble on himself.

One day, he stumbles on terrorists 11s who've stolen a military secret and is caught by a member of the Brittanian task force sent after them, who is Suzaku. As the rest of the squad arrives, Suzaku is shot for disobeying orders, while the military secret, a young girl, gives Lelouch the power to make anyone obey any order. He takes command of the terrorists and leads them to crush the approaching Brittanian force. However, Suzaku is secretly made the pilot of Brittania's brand new test model Knightmare, Lancelot. Lelouch becomes the masked king Zero to lead the rebellion to defeat Brittania.

Note: Storyline is a bit different than the anime.

An alternate Code Geass story in which Lelouch's fate is unknown after his meeting with C.C., whether he be dead or alive. Nunnally makes a Geass contract and gains the power to read the lines of the future. She also obtains a new body and takes up piloting an unusual Knightmare Frame.

The Empire of Brittania has invaded Japan using giant robot weapons called Knightmare Frames. Japan is now referred to as Area 11, and its people the 11s.

A Brittanian who was living in Japan at the time, Lelouch, vowed to his Japanese friend Suzaku that he'd destroy Brittania. Years later, Lelouch is in high school, but regularly skips out of school to go play chess and gamble on himself. One day, he stumbles on terrorists 11s who've stolen a military secret and is caught by a member of the Brittanian task force sent after them, who is Suzaku. As the rest of the squad arrives, Suzaku is shot for disobeying orders, while the military secret, a young girl, gives Lelouch the power to make anyone obey any order. He takes command of the terrorists and leads them to crush the approaching Brittanian force.

However, Suzaku is secretly made the pilot of Brittania's brand new test model Knightmare, Lancelot. Lelouch becomes the masked king Zero to lead the rebellion to defeat Brittania.

This series follows Suzaku's side of the story, while Lelouch of the Rebellion follow's Lelouch's.

4-koma parody of Code Geass featuring Lelouch Lamperouge as a part-time convenience store worker.

The January issue of Kadokawa Shoten's Newtype magazine is announcing on Thursday that Tomomasa Takuma (Code Geass: Nightmare of Nunnally, Kurogane Communication) is drawing a manga that is tentatively titled Code Geass: Shikkoku no Renya (Code Geass: Jet-Black Renya or Code Geass: Renya of the Blackness) next year. Goro Taniguchi, the director and story co-creator of the original Code Geass: Lelouch of the Rebellion television anime series, created the new manga's story concepts and is scripting the story. This is the first manga that Taniguchi is directly scripting himself.
The story takes place in the same official Code Geass history as the anime, but in a different era. The title character, Renya, is a 17-year-old boy with a mechanical left arm and shuriken throwing stars as his weapons of choice. The story begins when Renya encounters a mysterious, perpetually young witch named "Reifū C.C." C.C. has appeared in Japan's historical Edo era to seek a new partner for a covenant. Meanwhile, a mysterious man, with a striking resemblance to the character Lelouch of the original anime, also appears with unknown intentions.
The new manga is part of next year's new Code Geass project launch. Code Geass producer Yoshitaka Kawaguchi revealed on the franchise's website that the new project will feature the simultaneous releases of serialized comics, music, new products under development, and visual works.
(Source: ANN)

Yuuichi Tate is overjoyed: He gets to go to a brand new high school. Of course, then he just happens to find out the school he choose is under frequent attack by strange creatures called ''Orphans'', and the school set up a special task force of female members called ''HiME''s, using various elements as their powers, to battle these invaders. That's not all, though. Each member of the HiME task force has their own, unique ''Key'', another person whom, upon being discovered, can team up with the HiME to create a ''Child'', a combative unit specifically needed to effectively battle these Orphans. And with Yuuichi's luck, he just happens to find out he's not just the ''Key'' for one of the HiMEs, but for two... Two highly competitive, rival schoolgirls. And that's only the start of the trouble.
(Source: Tokyopop)

A rather chibi version of the original Code Geass with a similar setting but in the Bakumatsu Era.