The Modern Comedy of the NixOS Wiki
Sometime around 2010-2011, members of the Nix community decided to set up a wiki. Everything went well until (supposedly) people lost interest in maintaining the Wiki, and the overall quality of the Wiki began to dwindle as obsolete information accumulated.
On the 14th of november 2015 Rok Garbas gave the infamous talk "Make Nix Friendlier for Beginners" which to future generations became known as the "Kill the Wiki" talk. This rekindled the discussion about the decaying state of the official Wiki. An epic mailing-list discussion started 4 days later and some core developers seemed to agree that the Nix* manuals are a better place to put documentation, while others didn't.
Spam bots took over as there was no adequate protection mechanisms for the Wiki, increasingly demotivating contributors while the admins seemed lethargic towards the problem. Out of frustration Eelco announced the "Lockdown" of the Wiki on the 29th of August 2016. On the 9th of February user copumpkin opened an issue with the Request to unlock the wiki, another epic discussion started with almost a hundred responses but no outcome how to proceed with the official Wiki.
On May 9th the Wiki was permanently disabled when a PR by Graham Christensen was merged by Eelco. People started referencing to the Archive.org mirror of the Wiki. The last export of the original wiki is mirrored at archive.org announced on the mailing list.
To fill the void in the community contributor Jörg Thalheim (Mic92) started the nixos-users wiki on April 24th. Since Nixpkgs is hosted on GitHub, he opted to use the GitHub native wiki, allowing everybody who needed access to directly edit the wiki. This instance is known as the "first unofficial" wiki. Only a very small number of selected wiki articles were transferred from the original wiki.
Not long after, user Tristan Helmich (fadenb) started his own approach to resurrect the wiki by setting up a MediaWiki on his own at , mostly out of frustration of the bad UX of the github wiki (no table of contents, no search, etc.). The Wiki went online somewhere before May 2017 "on a lazy day at work" but he forgot to tell anybody about it. The only documented announcement is the twitter message "You can now log into https://nixos.wiki with your github account" with 8 likes and no retweets. The Wiki now has captchas enabled.
With the migration of the old MediaWiki to the new MediaWiki the project went a full circle.