20 Years Ago Aliens From The Planet Xeno, Were Sent Here To Wipe Out Humanity, But they wanted to toy with us first, They deployed these evil and violent creatures called headcrabs that infect the minds of the humans and turn them into feral monsters.
it has been 20 years since the original outbreak, humans are fending off the zombies and trying their best to hunt down the aliens aswell.

Alien Powers:
Speed
Mobility
Stealth
Claws
Vision

Headcrab Powers:
Infection
Mobility
Nightvision