Schwarzesmarken

They are both set in the same universe with Schwarzesmarken being a sort of prequel to Muv-Luv Alternative: Total Eclipse. The differences being that Schwarzesmarken is set in germany and being set about 30 years before Muv-Luv. 

Two nations in conflict, fights with mecha, the girl protagonist fighting for the union. 

In the case of Schwarzesmarken, we have the BETAs and human roaches on Terra Formars. Both shows deal with how humanity strives to defeat these monsters to save their own kind. While the main plot is about fighting the monsters, both shows also have twists where the root of the main problem is connected to human politics. 

Because winter seasons are apparently great for short dark military animes, dark settings, grey characters at the best, "realistic" magic/mecha warfare accompanied by convetional war as setting. 

Mecha, apocalyptic plot, strong military concept, fight with giant aliens/bugs. There is recommendation to muv luv alternative total eclips. I dont recommend that. That is pretty shitty, with nothing happening in research facility, just shiping making. While Schwarzesmarken, prior in same world as muv luv is brutal, raw with all military stuff and ptsd syndromes and relationships which belong to it, pretty similar to Blue Gender. 

Both are mecha, where there are monsters trying to destroy humanity 

* giant robots * military drama with a lot of deaths * edgy villains * cool CGI action * both are a good choice for the mecha fans to watch * both are based on light novels that are better than anime 

I find these two anime alike because of an alien attack being the major problem and it wasn't suprising to find the same artist in both of their opening themes. Also the protagonists seem alike, because they both have the urge to protect female characters and weaker people in general. 

have same heroine as symbol of freedom  

Both anime have an apocalyptic environment where our characters struggle to survive against the human threat known as: -Aragami (God Eater) -BETA (Schwarzesmarken) * It is largely about the members' struggles against the various monsters that come to invade. * The action and music stands out as much which is a credit to all the hardwork that has been established into the series. * They use a not so usual weapons [ 'God Arcs' in GE & mecha's in Schwarzesmarken ] * Horrifying and Awesome !!  

Both have awesome cast...Havia/Irisdina best team combo ever.... Both has gigantic war machines [ in Schwarzesmarken ~ Mecha's & in Heavy Object - Objects [ I love them so much :) ] Deaths, betrayals...secret services... logical and technologically advanced war... Both have likeable protagonists [Havia/Qwentur & Irisdina/Theodor...] Both are trully underrated gems... 

Takes place around the time of WWI/WWII Humanity puts aside the current war to battle monsters Only effective weapon against monsters are mechs Both are pretty dark in atmosphere but Gunparade does try to lighten the mood with some highschool romance  

Both anime have humans try to survive against mysterious monsters Both have an arrogant MC Both anime makes you feel like a character could die at any moment Both anime have gore