In the distant future, the human race is on the brink of destruction. Mankind, which now drifts in space aboard a massive, technologically-advanced base known as Avalon, is poised to launch one final, desperate attack against its enemy, the alien race Hideauze. It’s during this battle that Ledo, a mecha pilot, is thrown into a wormhole and sent to an unfamiliar place: Earth, the lost birthplace of humanity said to have turned to ice long ago. Having been saved by the inhabitants of the Gargantia, a fleet of ships that traverses the now-flooded planet, Ledo must come to terms with these primitive people with their backwards language and technology, learn to communicate, and try to find a way back home to his place in the sky.
After being threatened by extinction at the hands of alien invaders called the Zentradi, humanity undertook the task of guaranteeing itself a future by launching fleets of colony ships into space. On Macross Frontier, one such fleet, high school student Saotome Alto's life is changed forever: the fleet is suddenly attacked by unidentified creatures while he is performing aerial stunts for a concert by the wildly popular idol Sheryl. Alto quickly finds himself in the cockpit of a new-model fighter struggling to protect Ranka Lee, a young girl he met only hours earlier, from the invaders' swath of destruction. Noting his performance during this incident, the S.M.S. Skull Squadron private military company invites Alto to join their organization, where he continues protecting his friends and Macross Frontier.
No-brainer since both animes feature a large city that needs to be protected from an alien monster threat, a male hero with female friends and the balance of comedy and mech fights.
Both female leads are very similar, very open and friendly girls who have alot of fans.
Claude Kenni just wanted to shine free of his military father's shadow, a desire that made him take unnecessary risks. One of those risks whisked him off to an unknown planet full of monsters and magic. There, he met Rena Lanford, an energetic girl with mysterious abilites who believes he is a hero of legend. Soon, they're off on an expedition to find the cause of the monsters and the truth behind the sorcery globe all while hiding the technology he brought with him. Looks like Claude's got bigger shoes to fill than his father's!
I'm really surprised that no one at this point has made this connection - Star Ocean and Gargantia are extremely similar as far as a boy of science being forcibly transported to a more 'backwards' society that he has to get used to, while trying to find a way home.