SPHERE is a persistent gaming world Role Playing Game server that anyone can setup and run with up to 500 concurrent players online. The opportunity for adventure is limitless, and even small connection home users may host persistent games of up to 30 players with little to no game lag. Menasoft has discontinued work on this but it does live on. Go to sphereserver.com or spherecommunity.net for more.
Sphere has undergone a number of name changes and a very large amount of development since its beginning in 1997. It has been called Grayworld, TUS (The Ultimate Server), and finally Sphere.