Short answers, pulled from the story.
The first true rhythm game was PaRappa the Rapper, which arrived on the PlayStation in 1996. This title established the core mechanic of pressing buttons in the exact order they appeared on the screen to sync actions with music.
Dance Dance Revolution achieved large-scale success outside Japan in 1998 and became a global phenomenon. It was the only Bemani title to do so and used a pressure-sensitive dance mat to allow players to dance to the beat.
The rhythm game market experienced a nearly 50% drop in revenue by 2009. Sales of music games fell from $1.47 billion in 2008 to $700 million in 2009 due to market saturation and the late-2000s recession.
More than several hundred schools in at least 10 states have used Dance Dance Revolution in their curricula. West Virginia introduced the game into its schools' physical education classes to help combat obesity and increase energy expenditure.
Harmonix was acquired by Epic Games in 2021 and worked on a new rhythm-based game mode called Fortnite Festival. This mode was released within Epic's Fortnite game platform in 2023 and features Jam tracks that allow players to mix multitrack tracks from different songs.