The Alpha 15 Osiris multiplayer lobby is now discontinued. Users of Alpha 15 are advised to upgrade to the latest version.
The only distribution bundling Alpha 15 is Ubuntu 14.04 LTS, for which Alpha 16 is available in backports, and the latest version is available in our PPA.
Alpha 15 was released December 2013 with the subsequent Alpha 16 being out for a year now. The Alpha 15 lobby isn’t used very often anymore; the bot told users to upgrade to a newer version and we haven’t seen more than one player at once for more than a month. The Alpha 15 lobby bot also has an occasional issue causing it to terminate. Due to the inactivity, obsolescence, and amount of extra work required to sustain it, we have decided to discontinue the Alpha 15 Multiplayer lobby. By giving up support for our archaic Alpha 15 bot we are able to streamline some things on the lobby server as we do not need any special cases for the Alpha 15 bot anymore. Multiplayer via the Host/Join dialog is still possible for those who do not wish to upgrade.