After an experiment that goes horribly awry when an unexpected Resonance Cascade (an apparently completely fictitious occurrence) rips dimensional seams that devastate the facility, Gordon must fight to escape the now alien-infested facility as creatures from another world - known as Xen - subsequently enter through these dimensional seams. Gordon Freeman, a recent MIT graduate in theoretical physics, and also a recent employee at the titular Black Mesa Research Facility. As in Half-Life, players assume the role of the protagonist, Dr.
