Gordon's motivations during the Black Mesa incident went quickly beyond survival and into the realm of heroism, because he was willing to not just cower from vicious monsters and genocidal Marines like the other scientists, but actually fight back against them. He also had the determination to finish what he and the others had started by triggering the resonance cascade, even when confronted with incredible odds while on the path to doing so. Upon reaching the surface halfway through the first game (and after the worst ambush by Marines up to that point in the story), he could have understandably hotwired a car and hit the highway, never to be seen again... but he didn't. He could have refused to dive into the borderworld to hunt down Nihilanth, which had no guaranteed return to Earth and the implication that he'd likely never see his homeworld again... but he did it anyway. Members of the Lambda Team near the end of the game spell it out for him:
"Of course, you owe us nothing, Mr. Freeman. But you've come this far. You know as much about these creatures as anyone..." "Enough to know that if you don't wipe it out, there won't be much for you to come home to."
He knew what had to be done and that he was the only man that could do it. He couldn't just walk away with the fate of everyone and everything he's ever known at stake. This kind of conviction and courage was probably the very thing that turned him into such a mythic figure in the eyes of the resistance by the second game--especially since the resistance was founded by the very members of the lambda team that saw it themselves. However, this lead to a few expectations that bordered on the absurd in the second game: The meeting at the Little Odessa outpost basically involved a blustering Colonel suggesting they shoot down a devastating biomech helicopter with nothing but a single RPG launcher, something that had never been attempted before... and everyone in the room quietly and expectantly looking at Gordon at once.
...He did shoot it down, for the record. They even let him keep the launcher afterwards.
Clarifcation
Alignment: Thras.
Gordon's motivations during the Black Mesa incident went quickly beyond survival and into the realm of heroism, because he was willing to not just cower from vicious monsters and genocidal Marines like the other scientists, but actually fight back against them. He also had the determination to finish what he and the others had started by triggering the resonance cascade, even when confronted with incredible odds while on the path to doing so. Upon reaching the surface halfway through the first game (and after the worst ambush by Marines up to that point in the story), he could have understandably hotwired a car and hit the highway, never to be seen again... but he didn't. He could have refused to dive into the borderworld to hunt down Nihilanth, which had no guaranteed return to Earth and the implication that he'd likely never see his homeworld again... but he did it anyway. Members of the Lambda Team near the end of the game spell it out for him:
"Of course, you owe us nothing, Mr. Freeman. But you've
come this far. You know as much about these creatures as anyone..."
"Enough to know that if you don't wipe it out, there won't be
much for you to come home to."
He knew what had to be done and that he was the only man that could do it. He couldn't just walk away with the fate of everyone and everything he's ever known at stake. This kind of conviction and courage was probably the very thing that turned him into such a mythic figure in the eyes of the resistance by the second game--especially since the resistance was founded by the very members of the lambda team that saw it themselves. However, this lead to a few expectations that bordered on the absurd in the second game: The meeting at the Little Odessa outpost basically involved a blustering Colonel suggesting they shoot down a devastating biomech helicopter with nothing but a single RPG launcher, something that had never been attempted before... and everyone in the room quietly and expectantly looking at Gordon at once.
...He did shoot it down, for the record. They even let him keep the launcher afterwards.