I think if anyone's writing such a list, then for single PC you have to take into account EQWindows, EQPlayNice, and WinEQ, and similar software that worked with other games (FFXI windower etc). EQ1 originally only ran in full screen mode, so someone ("justsomedude") wrote EQWindows to force it into a window. EQ also did not feature any FPS limiting, so its CPU usage was always 100%, until EQPlayNice. When EQPN implemented Rendering Limiting, this dropped CPU usage even further by stopping the game from rendering the world in the background (thereby also increasing FPS the game actually ran at), allowing more clients to run with less power than it had previously taken to run 1. WinEQ started when EQWindows was no longer being updated, and pioneered Picture-in-Picture with instant window swapping.

And lol @ kate. I played MUDs from 1992 or so to 2000-ish. Never played more than 2 or 3 characters at once though, and definitely automated those. I cut my teeth on VikingMUD, an LPmud, and was a wizard (developer; I think LPC was my first experience with a language like C) there until I got banned. Apparently using your wizard to help a 2nd character level up is against the rules Mystic Adventure 2 (think it was a merc, offshoot of diku ) was the most fun I had in a MUD I think. Seems like people stopped playing it, or at least I did, after they banned "power levelling".