It's been months since the Human-Arume war started and ended, the war that brought mankind's civilization to collapse. The war only lasted a single day, with Arume ships that dwarfed buildings descending from the sky one day above the nations of Earth and opening fire with weapons only dreamed of in science fiction. Their goal didn't seem to be any resources or land or even something like a new planetwide resort, it was for extermination.
You are part of a guerrilla resistance that cropped up after every nation on Earth fell, the last hope of humanity. There are only a couple hundred million humans alive now that the resistance has knowledge of. Good luck, and rock and roll