I think I had a video game like this once
Strike Force Lightning, EDF operations here. You may notice that your PlayStation Vitas have been equipped with machine guns. Feel free to use them to shoot the hell out of the ravagers when they return in Earth Defense Force 2017 Portable on January 8, 2013.
And remember the best thing you can do is attack them while avoiding their attacks. Let's make those bastards go back to space. Destroy them all!