Games that have been identified as having proprietary or unique codebases (the root of a tree, if publicly distributed).
“Materia Magica (sometimes referenced as MM), originally named Moongate, is a well-known custom...Materia Magica
“Darkness Falls: The Crusade (1999), known informally as DFC and DF2, was an internet fantasy...Darkness Falls: The Crusade
“ForgottenMUD is a bilingual French/English MUD based on the Dungeons& Dragons 3.5 rules. It's...ForgottenMUD