I do this programming challenge every December, Advent of Code. It's a fun and increasingly difficult test, and a fun way to keep sharp or fumble through with a new language. I'm doing it in Ruby this year, because of the existing Gab social code. It's been a long time since I used it, and I was never really a big fan.

It's at https://adventofcode.com and if others are interested having a Gab leaderboard I started one, the code is 996979-b668457a