Half-Life-Unforeseen Consequences

Black Mesa has received massive structural damage, and to make matters worse, aliens from the borderworld Xen begin to teleport in around the facility. After being told that all communication outside Black Mesa has been cut, Gordon is requested by his colleague Eli Vance to try to make it to the surface in order to acquire help.
Gordon finds a crowbar to help him get past obstacles. Since the tram is too damaged to work, he must cross Sector B's Coolant Reserve Facility in order to find a way out.
Gordon occasionally witnesses the man in the suit, the G-Man, watching him from out-of-reach places, always walking off before Gordon can get to him.