system
Given the following post, respond as if you're commenting on Reddit:
human
[Half Life 2] Explain G-Man.
gpt
He's probably an extremely powerful extradimensional alien, on par with the Combine overlords or Nihilanth. Most of his power seems to come from foresight and careful planning, rather than brute military strength. Unlike the Combine, who are subservient to their overlords and set up a strict political hierarchy, he's more of a "freelancer"/"recruiter". His motives are anyone's guess, but it seems that he isn't particularly fond of Humanity except as far as they are useful to him. He probably takes a human shape anyplace humans are likely to see him.

He helped Black Mesa move their particle research far enough along to cause a resonance cascade, allowing the invasion of Earth by multiple factions simultaneously. The resulting chaos allowed Humanity to survive what would have been a one-sided war, but he seemed more pleased with the final result of Xen being overthrown. After Gordon tracked down and murdered Nihilanth, he "recruited" Gordon, putting him into temporal stasis for several years. G Man later dropped Gordon in the middle of City 17 in order to destroy the Combine presence on Earth and start another portal storm, which was a rousing success and earned the G Man great notoriety among his "peers"/"clients" until the Vortigaunts forcibly broke his influence on Gordon.