Team Fortress 2, Valve's free-to-play team shooter first released in 2007, built a huge inventory system around hats, weapons and other cosmetic items, so its item sounds became instantly familiar to players. Clips of drops, trades and unboxings spread across YouTube and later short-form video, where the chime was reused as shorthand for getting something good. It remains popular because it is short, clear and immediately associated with reward, making it useful far beyond TF2 gameplay itself.