The AR2, officially the Overwatch Standard Issue Pulse Rifle, is the main Combine assault rifle in Valve's Half-Life 2 from 2004, recognizable for its dark energy ammunition and distinctive secondary fire. Clips of its single shot have circulated on gaming soundboards alongside other FPS staples like the Fortnite pump shotgun sound, because the sound is instantly identifiable to players even without visuals. Its brevity makes it ideal for buttons and alerts, so it remains popular for streams, mods, machinima, and fan remakes long after the original release.