Why does Gordon do the things he does?

[elteaser]

Slight Spoilers ahead if you haven't played yet.

Here is a question. I'm playing. I am Gordon. I shoot the big rocket cuz the scientists say so. O.k. that makes sense. But then what? Why do I keep going down all these various corridors. Where is my destination? Why is that my destination? Have I decided to be a hero? Kinda unclear. Now I am infliltrating the army base. WHAAAT? Revenge? One man death machine? Hero? OMG.

[Sovereign]

The nuances of why he does what he does beyond simply wanting to reverse the mess Black Mesa caused is kinda up to you since he never speaks.

[CodySir]

The in-game reason why you can't leave the complex after firing the rocket into space is because the military is most likely guarding all the exits out of the complex. Plus, Its in a desert. How far do you think you're going to get wearing a relatively heavy radiation power suit? You'd be better off fighting through corridors, hoping to find some experimental teleporter to get you out than risk running a military blockade.

Have you ever watched Freeman's Mind? It also answers this question.

[pauls]

If you want to simply escape, play as Barney in Blue shift, thats his goal.

[Artek [General]]

I believe its all simply survival. After initial incident Gordon is simply trying to survive and get out of Black Mesa facility. As he progresses he probably realizes that world is in shambles because of the accident and there's nothing left but to try and clear up the mess.

I'm pretty sure the dialogue from various scientist NPCs also gives him his reasoning. He doesn't shoot the rocket or reach lambda complex by accident - NPCs directly tell him why he does what he does.
They launched the rocket in an attempt to get the portal storm under control, i believe... I'm not sure since i've alread forgot it, but there was a reason to do that. Something that we did again in Episode Two, might i add.

And we never infiltrate a military base. There is no military base in this game. Its all Black Mesa facility, simply overrun by both soldiers and aliens and we are walking through it trying to survive in order to reach the Lambda complex because supposedly (and NPCs tell us that almost directly, i believe) they have a plan on what to do. Mostly because their complex was responsible for discovering portals and Xen, so they had the most knowledge on what must be done in order to get situation under control.

After reaching Lambda it simply becomes the mission to try and take responsibility for what happened and clean up the mess that Resonance Cascade created by infiltrating Xen and trying to find and kill Nihilanth who's in charge of invading forces.
I'm sure Gorgon feels at least some kind of guilt over what happened, since he was the one who put the specimen into the scanner causing the resonance cascade. One could argue its guilt that's pushing him to do what he does. The rest is just trying to survive.

This reasoning extends all the way into Half-Life 2 episodes too.

[ERFANARCADE]

MY GOALS ARE BEYOND YOUR UNDERSTANDING !!!!!

[esopedantric]

Originally posted by S M O K I N G L I Z A R D S:

Slight Spoilers ahead if you haven't played yet.

Here is a question. I'm playing. I am Gordon. I shoot the big rocket cuz the scientists say so. O.k. that makes sense. But then what? Why do I keep going down all these various corridors. Where is my destination? Why is that my destination? Have I decided to be a hero? Kinda unclear. Now I am infliltrating the army base. WHAAAT? Revenge? One man death machine? Hero? OMG.

Adderall?

[True_Boredom]

Gordon does whatever you tell him to do

[BBSon John]

I am shooting Barney and scientists in the head

[Doc Tear Popper]

You don't actually get to meet Barney in HL1's events though.