[Axsuul]

This looks pretty cool. And since it hasn't been mentioned here yet, Advent of Code 2017[0] is ongoing right now and there's still enough time to catch up. But you can always go back to years 2015 and 2016 to sharpen a new language on.

I've been learning Elixir for this year's challenges and it's just the right amount of challenge required for understanding the idiomatics and idiosyncrasies of a language.

[0] http://adventofcode.com/