Itself a fork of ZDoom, GZDoom’s development dates back to 2005 and is led by Christoph Oelckers, known by the username Graf Zahl. Allowing for OpenGL rendering, amongst other quality of life improvements, it is generally considered to be the definitive way to develop and play Doom WADs (user-created mods and level packs) on PC. However, Oelckers has often been an abrasive figure in the community, going lengths without communicating with the team and abruptly declaring the end of the project at least once.
When Oelckers committed a change to GZDoom on October 14 aimed at detecting dark mode on Linux, his fellow developers confronted him about his use of ChatGPT. Although he claimed that he had unintentionally pushed his change to the master branch of GZDoom instead of a test branch, between his attempt to conceal the update by only disclosing it in comments within the code and the general dubiousness of using code generated by Large Language Models, this proved the final straw for much of the team. Later that day, UZDoom was announced in the ZDoom Discord community server (as reported on by Gaming on Linux), promising “a more stable development structure with healthy collaboration and less power given to individual ‘project leads.’”
At present, the GitHub page for UZDoom is identical to that of GZDoom (minus the controversial commit), all the way down to the thanks for the README template and GPL3 citation, but is likely to diverge in time and replace GZ as the recommended way to play Doom on modern computers.