The sound comes from the Stalker enemy in Half-Life 2, Valve's 2004 first-person shooter. Stalkers are one of the game's most disturbing figures, so their scream stuck with players long after release. The clip later spread through game meme culture, especially in GMod videos, Source engine edits, and YouTube compilations. It is still used because it delivers instant dystopian horror in just a couple of seconds, while also carrying a nostalgic punch for fans of Half-Life and older PC gaming memes.