Complex sentence: As with Gearbox's previous expansion pack', "Blue Shift" returns to the setting and events of the original game, but portrays the story through the eyes of a security guard, Barney Calhoun, employed by the Black Mesa Research Facility.
Split into simpler sentences: As with Gearbox's previous expansion pack', "Blue Shift" returns to the setting and events of the original game, but portrays the story through the eyes of another person. The protagonist in "Blue Shift" is a security guard, Barney Calhoun, employed by the Black Mesa Research Facility.