You are a space trooper. Your crew finished the cleaning mission and left you alone by accident. Now you are surrounded by aliens. They're not going to judge you or something, they just want to tear you apart in pieces. Prepare to die?
Fight them as long as you can. Your crew may help you later. Maybe one of squad members were also left here?
You have an arsenal of five weapons, which can be loot from bosses. And aliens will sometimes drop some other weaponry if not damaged.
That's it. Good luck.