Call in. A single player mod which plays out at the same time as Gordon and Alyx flees the citadel in Ep1. You take the role of a rebel soldier on a mission to retrieve information regarding the super portal to aid in the building of Dr. Magnussons rocket.
Is that zombie hiding behind the metal plates? Poor chap... Been so embarassed after the whole "headcrab" thing popped in around puberty...
xD