Each year since 2017 I've been participating in Advent Of Code, an advent calendar containing programming puzzles. For more information on what AoC is all about I highly recommend checking it out here: https://adventofcode.com/about
In my free time I really enjoy solving all kinds of puzzles, and AoC is a great opportunity to combine this hobby with my professional skillset. I don't aim to compete for any spots on the leaderboard, instead my primary goal is to solve all the puzzles and have fun doing so. For each year I also try to pick a specific skill I want to learn or improve over the course of the puzzles, e.g. a new programming language or library I'm not yet familiar with.
Most of my solutions are available on my GitHub. But beware, due to the short-lived nature of those puzzles the resulting code tends to be quite messy ;)