It is 13 months after the incidents at the Black Mesa Research Facility. While the nation never got know what happened there, the facility is no more and a new organisation has been founded to discreetly handle all "alien related topics". It is formed of the best scientists, technicians and military forces worldwide, and its name is Poke646.

You play in the role of Damien Reeves, a low level technician in the Poke646 tech department. When Poke646 scientists suspect an imminent alien invasion in Nation City, Damien assists in setting up huge generators all over the city to drive back the alien forces and destroy their portal technology.

But as it often turns out with seemingly brilliant plans, this venture fails. Even worse, Damien is accidentally being left behind in a capital crowded with aliens and soon becomes Nation City's only hope to defeat the alien invaders. And on your way you'll find out that this is only half the truth...