Line Rider was briefly popular a few years ago, if anyone remembers. There's a Youtuber who's made a few videos using Line Rider and syncing it to popular classical songs.
This one's my favorite, mostly because I like Grieg's In the Hall of the Mountain King:
I think these are pretty fun to watch, they're so artistic and Line Rider is an unwieldy medium. I guess the guy who makes these spends a few months doing each video. It's all trial and error, redoing each line until the rider does exactly what it's supposed to do.
In these next ones, he got the creator of Line Rider to program multiple riders. I can't even get the thing to travel down a single hill, and this guy is juggling multiple riders, synced to music, sometimes with the riders and their sleds off screen for several seconds. It's a delight to watch! The time and patience it would take to make these blows my mind.
This is Dance of the Sugarplum Fairy from The Nutcracker play/ballet:
And Beethoven's 5th Symphony: