What you would do, if everything seems to be over and you are still alive? We are pretty sure you'd like to come home. The story takes place in Half-Life universe, after being a lab rat and death of mental ai system, you should make your way in the wake of last alive members of "Aperture Transport Systems", subdivision of "Aperture Science". They're barricaded in Institute Campus, which is located on volcanic island. However, after a while the portal storm has begun, which brought Combines, Headcrabs and Antlions.