Obsidian



Obsidian was a source port and a fork of Chocolate Doom by tm512 that aims to be a "thin server" multiplayer port. It puts in new features that don't deviate too far from classic Doom, however, it is still in early development and it will likely stay like that for the saleable future as the last time the port was updated was in 2011, along with this, the official Bitbucket for the port now goes to a 404.

You can join up to the port's IRC at #obsidian on irc.oftc.net if you have any questions, but seeing that the port has not been updated in a long time, it is questionable if anyone will be there; joining the Chocolate Doom Discord server might help you get a better reception for it.