it's a shame clan lord[1] from delta tao software is omitted, although I understand you can't document them all. its historical significance comes from being the first graphical MMORPG for mac, having started in 1994. it still runs to this day, and because there's no exp cap there are people who have been playing the same characters for 20 years. the hand-drawn sprites hold up surprisingly well (even if the game only moves at 4fps), the world is massive, and its stories and history are rich. some puzzles/quests remain unsolved after all this time.
1. https://www.deltatao.com/clanlord/screenshots.html