Hi there,
You might be interested by this article: https://github.com/blog/1972-the-game-has-changed
GitHub launches a new "Game Off", its yearly game jam which seems to be (IMO sadly) focused on browser games.
However, I find a little gem in the links given in this article. Someone created a GitHub repo to list open source games being hosted on GitHub, and of course you're free to help complete the list using pull requests (I just did one to get OpenDungeons, MegaGlest and The Secret Chronicles of Dr. M. added to the list). Here's the link: https://github.com/leereilly/games
Enjoy! :-)