MUDs - where do they come from?

Are you looking for a historical reference, or something deeper then that?

Purg pretty much got it right. MUDs also doubled as college projects for coders looking to show their chops and get their game on. That is why the major MUD codebases are all licensed non-profit. They were required to be because they were run on college servers and done as college projects with these very large teams of students.

There were some single-player text games back in the early days of personal computing. One day, someone worked out how to connect a game like that to some university network or whatever, and local MUDs were born. Often they were just talkies, not much gameplay. Then in the 80s, some started to design their MUDs to be more game than chatroom. DIKU was developed in the late 80s in Denmark (Datalogisk Institut Kobenhavns Universitet) by people whose names you still see when you log into any DIKU-based MUD (Katja Nyboe, Sebastian Seifert, etc.) Since the internet as we know it was starting to become a thing around this time, it led to an explosion in public online MUDs built on DIKU. While DIKU wasn't the birth of MUDs as D&D-like games, it was definitely a pioneer for plug-and-play stock code. The branches of the MUD tree that preceded DIKU were mostly homemade codebases that weren't very practical for others to pick up. DIKU brought like a 5000% increase in the number of MUDs.

In the beginning, MUDs of the same codebase were pretty similar to eachother. People didn't get too adventurous with their code customizations. Usually the areas, NPCs and items would be unique, but the classes, skills, spells and general game mechanics would be mostly stock. One of the big decisions for MUDs at the time was whether or not to allow equipment to be saved on logout, and you can still see "equipment saves on exit" listed as a feature on some MUD sites to this day. More codebases started to crop up and branch out further into sub-genres until it got so muddled that DIKU remains the only universally recognizable "brand" in the MUD community. This stems in part from fact that the DIKU license prohibits monetization of any MUD built on the codebase. Back in the late 90s when MMORPGs were becoming a thing, a bunch of MUDs suddenly tried to monetize as well which caused many players to deliberately seek out DIKU MUDs because these would always be free.

Armageddon began somewhere around 91-93, I can't remember. It wasn't until like 96 or so that it really became a roleplaying game. Prior to that, it was pretty normal on MUDs for most players to be kind of in-character, though not really the kind of RP you'd see on an RPI, and it wasn't usually enforced by rules. People would just talk in an accent and put up tacky fantasyesque who-titles and stuff like that. Then little by little, Armageddon became more about roleplay and realism. The RPI ruleset gradually formed and then gave rise to a genre of MUDs following the tenets of permadeath, always-IC, no exp/levels, etc. That's how you got Harshlands which had a very unique and extremely RP-centric code. This was used to make Shadows of Isildur which was Armageddon's main competitor around 2004-2010. One day some staff split away from SoI to start AtonementRPI, and around this time the code was restructured into the open source RPI Codebase which Shadows of Isildur now uses. That's the abridged history of RPIs. There have been other ones like The Inquisition and ParallelRPI, but the main timeline of the RPI tree goes Arm>HL>SoI>Ato>SoI2.0 where it has kind of ended while FutureMUD is in development.