Killpocalypse comes from Halo: Reach, Bungie's 2010 first-person shooter for Xbox 360, where its multiplayer announcer calls out rare multi-kill medals earned during a single life. As players shared montages and clutch clips online, the call became shorthand for an unstoppable run, even outside Halo matches. It remains popular because it carries instant recognition for shooter fans and a sense of escalating achievement that a simple kill sound cannot match.