The Combine are the alien-backed enforcement forces from Valve's Half-Life 2, released in 2004, and their distinctive damage grunts and armor sounds were extracted from the game's files by fans. Numbered clips like Combine Hit 7 spread through Garry's Mod, Source Filmmaker and soundboard communities, where short Source engine effects became a shared library for machinima and edits. The clip remains popular because it is instantly recognizable to Half-Life players, cleanly recorded, and short enough to layer over any impact without overwhelming dialogue or music in a video.