Advent of Code is an awesome coding puzzle challenge by Eric Wastl. Every year, in December, Eric and his team put out some funny Christmas-themed coding challenges. There are public and private leaderboards, so you can challenge your friends and colleagues.
AoC's goal varies between coder and coder, personally it's an opportunity to learn a new language: this year (which is actually my first) I will focus on Golang.
If you wanna contact me please feel free to hit me up on my public email or on my Telegram