Approach the light... Enter the world that is outside Aperture... Free yourself... You are [SUBJECT NAME HERE] from [SUBJECT HOME-TOWN HERE]. After volunteering to take part in the Aperture Science Hand-held Portal Device tests, you notice something strange. In your head, something tells you that boxes shouldn't be orange, portal-guns shouldn't be red and security cameras shouldn't have blue eyes. Continuing anyway, a seemingly friendly robot called GLaDOS starts to guide you through the tests... As you finish however, in a attempt to get rid of you, she tries to kill you. Not succeeding however, you escape into the bowels of the Enrichment Centre. In a final stand-off against you and GLaDOS you defeat her and get dragged off unconscious by a "Party Associate". As you fall down through a old, unused vent, you land down in an different chamber. Can you escape?
Note: The new particles are not for use in the test chambers, they are for something different.