I think what made the eternaut so harrowing and scary and realistic was that the aliens do actual warfare against the humans, they would learn and adapt.
Usually in movies humans figure out the aliens weakness, they learn how to turn their weapons against them and thats it, war over.
In here every time the humans learn a trick to counteract the aliens the aliens adapt, they switch things up, they try again this time having fixed the bug that let humans win last time.
I think one of the best examples of how stupid war can get is one whole section where they finally find the base of the aliens, and this base is being constantly bombed with nuclears by the first world powers but the aliens have ways to disable nuclear bombs before they hit. Eventually our heroes manage to force the aliens to retreat, problem is our argentinian heroes have no way to communicate with the military forces in the USA that the aliens retreated (this is back in 59 so satellite imaging and international communications were a lot harder, and the heroes were a small resistance of civilians) so they keep sending bombs and eventually buenos aires gets nuked even though the aliens are gone.
And then the aliens come back and kill the rest.
