As the next Advent of Code is still 5 months away, I decided to build my own programming puzzle game: Marches & Gnats (https://mng.quest)
It's a browser-based game where you solve challenges using a Turing machine and eventually create a higher-level programming language on top of it. The story is set in 19th-century Estonia (so hopefully you'll learn something new about my country's history along the way).
I built it with Django and django-unicorn.