The second official expansion for Half-Life, again, like Opposing Force, developed by Gearbox under VALVe's supervision, pits you in the role of one B. Calhoun, member of the Black Mesa Security Force, as he begins another long shift just minutes before the Resonance Cascade.

Set in the first hours of the catastrophe and not long after HECU's arrival in the facility, the game revolves, unlike two previous games, around simply getting out of the facility alive with the help of doctor Stanley Rosenberg, his three colleagues and an antiquated teleporter in the abandoned sections of the base.

Unlike Opposing Force, Blue Shift does not introduce any new weapons, enemies or gameplay, instead concentrating on creating a self contained, stand alone story set in the crumbling Black Mesa research facility. You will meet the same aliens and soldiers and eliminate them with the same weapons as in the original Half-Life, but in new and previously unseen surroundings, as well as learn more about the facility itself.

And in the end, as always, it's you, your wits and a hostile world bent on relieving you of your duty.