The Earth Defense Force, a unified multinational military sponsored by nearly every country, is founded after detecting an impending alien visit in case the aliens prove to be hostile. In the year 2017, that proved to be true and the EDF fought against the Ravagers, an alien race that attacked Earth with giant insect-like creatures, UFOs, robots, and gigantic, 120 foot tall lizard-like creatures. Eight years after defeating the last Ravager in Arizona, they attack again with new creatures, evolved from their underground nest. Among them is the Retiarius, a spider-like creature which makes gigantic spider-webs, and giant bees. In the year 2025, the EDF must protect the Earth again from the alien invaders.