Half-Life, released by Valve in 1998, made Gordon Freeman famous as a silent scientist hero working at the Black Mesa facility, where scientists and guards routinely greeted him by name. Those short NPC lines became easy to rip, remix and reuse, especially once Garry's Mod turned Half-Life assets into a sandbox for machinima, roleplay and meme edits. The simple hello survived because it is instantly tied to Gordon without needing dialogue from him, so players still use it as a nostalgic shorthand for spawning in, meeting an NPC or starting a scene.