Gargantia on the Verdurous Planet

Average 7.4 across season 1

While fighting an intense inter-galactic war, a mecha pilot is accidentally warped into a space-time neither he nor his computer recognize. After waking up from a long-time hibernation, he finds himself trapped on a planet, with human residents talking in an unknown form of language, using inferior technologies, and - most shocking to him - naturally breathable air.