Thank you that pointing out that UO was not the first MMO. It was the most successful MMO for its time. I played one of the previous two, Neverwinter Nights on AOL Dialup. My friend played another called Meridian Online. NWN was so popular there was a que for the server ALL the time. That's a lot for $1.59 a minute!
NWN was D&D based system. Level based with classic d&d classes. It was fucking TIGHT. There was PVP in the best dungeons. However, it was mostly consensual. They abruptly canceled the game because of a negotiation issue with Wizards of The Coast.
http://en.wikipedia.org/wiki/Neverwinter_Nights_%28AOL_game%29Meridian Online has the exact same ruleset as early UO days. It just didn't have housing or horses. It played like doom. It also had a regeant system that was very identicle to Ultima Online.