Stalkers are unsettling enemies from Half-Life 2, Valve's 2004 first-person shooter, known for their distorted, human-like cries as they stalk players through dark industrial areas. Their scream became recognisable to players long after the game, and online editors later slowed it down and added reverb, a popular treatment that makes game audio sound heavier, dreamier and more ominous. That slowed version now circulates in horror edits and meme videos, where the familiar game sound is repurposed as a standalone scare or punchline.