Graphical MMOs that predate it are Habitat (1986), Neverwinter Nights (1991), Meridian 59 (1995), The Realm (1996), and Ultima Online (1997). In 1999 when Asheron's Call and EverQuest came out, games like this became obsolete.
But there are still a few hundred players of Sierra's The Realm, which first came out in 1996.
There are also many community emulators for Ultima Online.
Actually CL existed long before 1999 -- I know that very well. I don't have an exact date; the 'official' release date was 1998, but it was just a rubber stamp thing; it had been functioning in Beta mode for several years before that.
The release date was just a question of resetting everyone's characters and starting again on a (must slower) experience path.
Not to forget Tibia, which was released in January 1997, is still developed and run by the same company and has thousands of concurrent players at any time of the day.
But there are still a few hundred players of Sierra's The Realm, which first came out in 1996.
There are also many community emulators for Ultima Online.
https://en.wikipedia.org/wiki/Habitat_(video_game)
https://en.wikipedia.org/wiki/Neverwinter_Nights_(1991_video...
https://en.wikipedia.org/wiki/Meridian_59
https://en.wikipedia.org/wiki/The_Realm_Online
https://en.wikipedia.org/wiki/Ultima_Online