Warframe is a free-to-play cooperative action game from Digital Extremes, first released in 2013, in which players take on missions against factions including the Corpus. Bursas are the Corpus faction's heavy, shielded robotic units, deployed as reinforcements during certain missions, and their arrival is signalled by a distinctive in-game alert. Clips of that warning have circulated among Warframe players as a shorthand for trouble arriving, and creators outside the game now reuse it whenever they want a short, recognisable signal that backup, or a problem, is on its way.