What do you think was the thing that Adrian Shephard witnessed that the G-Man had to nuke Black Mesa and silence any witnesses for? Was it Race X or the incident in general? Or even the knowledge of the G-Man's existence?
I still question what the fuck they were doing to that Bullsquid in the Alien Quarantine Labs from Half Life: Decay.
Here's a good question, what do you think happened to Adrian Shepard after Opposing Force? Was he assigned to prevent a second invasion by Race X? Or did is Return to Ravenholm still canon?