Playing Favorites: 2K Boston's Ken Levine

IndustryGamers continues their "playing favorites" feature series by convincing 2K Games' Ken Levine to offer up his personal list of favorite video games. Among them are Master of Magic, Baldur's Gate II, Ultima Underworld, and World of Warcraft. Guess which:
The game that inspired System Shock and BioShock. The game that made me decide I had to be a game designer. It's really the first virtual world. And you never forget your first, do you?