Muv-Luv Alternative: Total Eclipse

In 1973, an invasion of aliens known as BETA landed on Earth and began driving human civilization into nearly collapse. Facing an enormous mass of enemy force, mankind developed large humanoid arms called as Tactical Surface Fighters and deployed them to its defense lines through out the world. However, all those efforts could slow down defeats but could not stop BETA, and mankind is forced to abandon major areas of the Eurasian Continent. For 30 years, mankind is bogged down in an endless war against BETA without any hopes of victory. Yui Takamura, a TSF pilot of the Imperial Royal Guards of Japan, is given responsibility to develop the next TSF unit and sets off to Alaska. Meanwhile, Yuya Bridges, a TSF pilot of the U.S. Army, is heading to the same destination.

Synopsis from Anime News Network