Mild suspicions regarding the intent of the story and script writers aside, Universe at War does a number of things right, and it's worth making sure those are writ large from the outset. Firstly, it dispenses entirely with the idea of plucky humans fighting off an interstellar invasion. In this game, humanity forms the tutorial levels - the real fighting is all about the aliens.
Crush the puny humans like insignificant insects! Evil cackling is the order of the day where the Hierarchy are concerned.
So, you control a band of US marine types for long enough to learn the controls - and then they're promptly shoved to one side when it becomes clear that the first remotely powerful alien unit to come along will annihilate them. The game proper only begins when the Novus, a race of gleaming silver robots, turn up to challenge the invasion of Earth by the Hierarchy, a race of giant multi-legged biomechanical walkers.