never heard of it until today, thanks to Bea. if you're into programming puzzles, you should check it out. i know i will be (but probably not all the puzzles)
"Advent of Code is an annual set of Christmas-themed computer programming challenges that follow an Advent calendar. It has been running since 2015. The programming puzzles cover a variety of skill sets and skill levels and can be solved using any programming language."
~ Wikipedia