One Hour One Life

One Hour One Life is a multiplayer survival game of parenting and civilisation building.

The game is entirely free software, with everything, including the server software and all media, being released into the public domain.

Buying the game from the author is required to access the official game servers, and also provides easy access to pre-built binaries, which are regularly updated.

Having acquired viral status on YouTube, it might well be the most well known libre game.