Like last year, Evennia, the Python MUD creation system, takes part in Hacktoberfest, a yearly event run by Digitalocean in collaboration with GitHub.
The premise is simple: Sign up at their website and then contribute with 5 GitHub pull requests during the month of October. If you do, you'll win a unique T-shirt!
You can help out any OSS project to win, if you want to help out Evennia, I have marked a bunch of suitable issues with the Hacktoberfest label for you to sink your teeth in.
Code on!