Simutronics Corp.

From the website:

Simutronics Corp is a leader in the business of massively multiplayer games, focusing on persistent worlds using a subscription-based model. Incorporated in Virginia, Simutronics has offices in the St. Louis, Missouri and Washington, DC areas with more than 300 employees and contractors around the world. The company is privately held. 

Simutronics is one of the pioneering companies in this dynamic field. Founded in 1987, the company has seen more than a million paying players through the Web, Microsoft's MSN Gaming Zone, Prodigy, CompuServe, America Online, and GEnie. Development partners over the years include most of the leaders in the online, media, and computer game industry including Universal Studios, Sony, Viacom, Time Warner, and Microprose.