It is on a freeshard or player run server. There are a whole host of them but this one is going to be fresh and fairly populous at launch. The other great thing is the game has changed over years in an attempt to be more WOW like and this one brings it back to its roots.
www.game-master.net is the website, it certainly looks like something out of the early 2000s. The ClassicUO client works on Mac if you are into that sort of thing.