Project Zomboid is a hardcore isometric zombie survival game developed by The Indie Stone, in development since 2011 and in Steam Early Access since 2013. Build 41, released in 2021, was its biggest overhaul, adding new animations, combat and a revised skill system where this jingle marks character progression. As clips of long survival runs spread on YouTube and Twitch, players began lifting the sound for other games and real life edits, turning a quiet in game reward into a widely recognised shorthand for levelling up.