Originally it was the TMI-2 mudlib running on MudOS [1], though my understanding is that they heavily modified the codebase over time. The library was never off

Originally it was the TMI-2 mudlib running on MudOS [1], though my understanding is that they heavily modified the codebase over time. The library was never officially released as open source [2], but the code (in C) is included in a ZIP file alongside installers and related files [3]. As for the JavaScript client, it appears to be proprietary. [1] https://t2tmud.org/boards/news/1402345353.php https://t2tmud.org/boards/news/1402345353.php [2] https://en.wikipedia.org/wiki/LPMud#TMI_Mudlib https://en.wikipedia.org/wiki/LPMud#TMI_Mudlib [3] https://mudbytes.net/files/view/1041 https://mudbytes.net/files/view/1041