In 2010, the Britannian Empire enslaved Japan using powerful mecha known as Knightmares; in the aftermath Japan was renamed Area 11, and its people began a hard and terrible existence. Lelouch, a Britannian student living in Area 11, has grown up hating the Empire and everything it stands for. One day, in the middle of a terrorist attack, Lelouch meets a mysterious girl who grants him the ability to control minds. Can he use his new power to fight for freedom, or will his hatred twist his good intentions into mindless acts of vengeance?
Centuries ago, humanity carelessly ravaged the Earth’s environment, forcing them to leave and form a colony elsewhere. To prevent the same mistakes from happening again, they allow a supercomputer to run their lives. Children are genetically engineered and at the age of fourteen take ‘adulthood exams’, a process whereby the supercomputer ensures they are suitable for membership in this perfect society. Those who pass have their memories erased and are guided into the next stage of their life; those who fail are immediately destroyed. Jomy is a boy about to take his adulthood exams, but things go terribly wrong when a man wreathed in light interrupts the process. He is a Mu -- an aberration, a new generation of human with extraordinary powers usually detected and eliminated by the supercomputer. This man tells Jomy he too is a Mu and introduces him to the Mu society. They are a rebel group in hiding from the oppressive human regime, who live in the hope that they will find a life of peace on Earth some day. Can Jomy leave behind all that he has known, come to terms with his awakening powers, and help the Mu return to their beloved Terra?
I recommend Toward the Terra after Code Geass because I think you are looking for another intelligent sci-fi anime that offers similar levels of emotional engagement, asks difficult questions, and has imperfect protagonists. Whilst Code Geass leans heavily on shocking twists, Toward the Terra is a subtler, more epic look at humanity's potential and pitfalls. Code Geass will have you gasping at the end of every episode; Toward the Terra will have you choked up or cheering. This doesn't mean there aren't stunning battles involved - just swap the mecha for space ships and psychic powers. Anyway, I regard these two as equally powerful.
The power to cross over dimensions is one that is deeply coveted -- a lesson that childhood friends Sakura and Syaoran learn the hard way when an unknown enemy attacks an archaeological dig in their country. As a result, Sakura's memories are scattered to different dimensions, causing her to fall into a deep sleep. In order to save Sakura's life, she and Syaoran must journey to various worlds in search of her memories, with the help of fellow travelers, Fai and Kurogane. But finding Sakura's memories won't be easy, and the price for traveling through time and space is high...
Even if the series are completely different in plotlines, times, and genres, they are still closely related in drawing style, characters, and sound. It's a long shot, but I have a feeling you would enjoy Tsubasa Chronicle as well.
Humanity has stretched its reach into space and has settled onto a number of planets. For the past several hundred years, though, most of man’s territory has been politically and militarily dominated by the Tytania clan. However, their grip of power begins to shake when an admiral from Euria, Fan Hulic, preposterously manages to win a battle against an armada commanded by a Tytanian duke. Now wanted by Tytania, Fan Hulic flees from one planet to another. His travels will lead him to many places and many people, all of whom finally have hope that the hated Tytania can finally be defeated.
Code Geass and Tytania both tell similar tales. Tales of a downtroden public, lorded over by a powerful elite body of individuals. Whether it be Pax Tytania or Pax Britannia, at some point enough is enough and the downtroden begin to fight back. In both worlds, a single man, recognized by many as a genius, becomes the catalyst for this change.
While Code Geass is slightly more action oriented, both series have similar levels of political intrigue and plotting. It is my firm belief that if you enjoyed Tytania, you will enjoy Code Geass and vice versa.
In post-war Japan, the nation remains unsettled and crime is as big a problem as ever. Despite his sharp mind and keen deductions, "Defeated Detective" Shinjurou Yuuki frequently loses out to his rival, Rinroku Kaishou, whose information network has previously aided many police investigations. However, in spite of his poor reputation, Shinjurou continues to work on every case he's recruited to with his mysterious assistant Inga. With Inga's power to transform into a being capable of forcing any person to truthfully answer one question put to them, the pair uses everything at their disposal to get to the bottom of each crime and reveal the true culprit – even if the reality of who solved the case never reaches the public...
It both series, you have the lead/s, in Code Geass Lelouch and in Un-Go Inga and Shinjurou that use intricate plots to bring down their foes instead of weapons (mostly). The most striking similarity is Ingra's "eye" ability to make a person answer 1 question, and Lelouch's Geass to make people do 1 thing.
As far as personality goes, Lelouch is sort of split into two with Inga and Shinjirou. While Inga is sort of crazy and has the eye power, Shinjirou is smart and calm. So far, I really like Un-Go, and Code Geass is one of my top favorites, so watch them both, no matter what you like.
The Nation of Gallia has always remained neutral in conflicts and has only gone to war to defend itself. However, as war flares between the East Europan Imperial Alliance and the Atlantic Federation, Gallia is soon targeted for its abundance of ragnite ore, a versatile and hugely valuable material. The Civilian Militia is soon called into action, and Welkin Gunther - son of a legendary war hero - is named leader of Squad 7. Under his command are the headstrong and practical Alicia Melchiott; the sharp-tongued Brigitte Stark; the grizzled veteran, Largo Potter; and Welkin's adopted sister Isara, whose Darcsen heritage means she faces prejudice, even from members of her own squad. With the rest of Squad 7 and the mighty tank Edelweiss, they must do their best to defend Gallia.
Well, Valkyria Chronicles is simply the seinen version of the Code Geass serious. The mechas and superpowers found in Code Geass are substituted for tanks and an ancient race of superhumans that appear later in the show. Both are very dramatic, and militaristic, but Valkyrie has a bit of fantasy and romance intertwined, and is a bit more dramatic, and contains less action, but enough to match the theme of war. Also, I should note that Valkyria Chronicles takes place in 1935 Europe, while one of Geass's settings involves a sci-fi version of Brittania, which is simply an archaic name for Britain, which is a part of Europe.