His latest game, "One Hour One Life" [3], is a massively multiplayer online game where your character has only one hour of life. You start off as a baby and are dependent on others for shelter and heat before you're able to be autonomous. Eventually you die of old age but your impact on the world/server persists.
I recommend anyone interested to purchase the game [4] or at least look at video stream of gameplay [5].
When I purchased the game, the source code came with it and as far as I could tell was dedicated to the public domain. This was client code so I'm not sure if the server code is released anywhere (maybe this was what was taken down at GitHub).
[1] https://en.wikipedia.org/wiki/Jason_Rohrer
[2] https://en.wikipedia.org/wiki/Passage_(video_game)
[3] https://en.wikipedia.org/wiki/One_Hour_One_Life
[4] http://onehouronelife.com/
[5] https://www.youtube.com/watch?v=Hu7kXKuShks&list=PLcA1QDRup-...