You are a brave space trooper. You are here to destroy a lot of aliens. Your mission is to clear an enemy sector.
If they keep going, fight them as long as you can. There are only a couple thousands of them, so its not a big deal... probably.
Your company has developed a brand new weapon that absorbs dead enemies energy and makes you able to kill more and more of them. And youre so lucky to test it.
You have to return alive to deliver gathered results.
Dead enemies drop some microcircuits (if not damaged) that can be implanted into your ship to improve its durability. They can also drop some stolen from humans written-off ammunition if they have some.