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?
In the future, mankind is divided between two powers: Union, and Deague. For the young Sarah Werec, watching her dearest brother Ralph depart for the front lines of the war was a fate worse than death; for even if he were to survive, the 130 light year distance between them dictates that even if he were to return, she would be long since deceased. Thus, in an effort to see her brother again, Sarah sets out to become a pilot of the Strain – Union’s mecha force; but on the eve of reaching the first step to her goal, her only chance to succeed is stripped from her. Haunted by the many ghosts of her memories, Sarah must now endure an endless series of sacrifices as she struggles to discover the truth about her brother...
Both Soukou no Strain and Code Geass have the same basic components:
First, great characters with tragic pasts. Both anime feature two dimensional characters who are actually affected by their past. Both Lelouch (Our manipulative and tragic hero of CG) and Sarah (Our somber, haunted heroine of SnS) have had everything they thought they knew flipped upside-down.
Second, trilling, fast paced plots with lots of action. Let's see here... Mechas? Check. Check. Guns? Check, and Check. Blood and Character Death? Check and... Check!
And last, The Romance Factor. Both anime have no real set pairings, and let the fangirl imaginations take over in the matter. But they both include kisses and interesting situations~
Ten years have passed since the demise of the bubble economy, a time that polarized the world into two groups of people: the rich and the poor. In the present day, Saiga Tatsumi (a former war photographer) has been hired to investigate a secret club for the rich named the Roppongi Club, but he soon discovers secrets much darker than he’d ever imagined. With the help of a exploited goddess named Kagura, Saiga now possesses the power to kill by simply taking a photograph; but can he stay alive long enough to save her from her captors?
In a world of science, sorcery is rediscovered and rapidly adopted in all areas of industry – but at a high price: an invisible pollution is spreading out across the world. Those who do not take proper precautions become infected, lose their sanity, and become demons. The Sorcery Administration Bureau, along with their Tactical Sorcerers, monitor magic uses and respond to any demonic outbreaks that occur. In this world, Ray Otto is a rogue tactical sorcerer who hunts down demons with reckless abandon. Given that he always gets the job done, the administration generally lets his activities slide. Together with the mysterious girl Kapel Theta, Ray risks his life and humanity to destroy demonkind... when the price is right.
Strait Jacket and Code Geass: Lelouch of the Rebellion take place in worlds that are filled with monsters, one literally and one figuratively so, and follow the paths of two men who fight to destroy them at any cost. The methods they use are different, and the enemies certainly don't look the same, but the inherent darkness in these shows and the truth about how one becomes a monster really bind these shows together.
Show may be different due to it's differences but the main Characters Lelouch and Suzaku's ideals and friendship are similar to Yuri and Flynn where Lelouch and Yuri wants to change from the outside and Suzaku and Flynn wants to change within. Both are awesome where it involves battles, politics, corruption, drama, blood, loss of allies, and friendship.
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.