Its original continuity. It is X-Men taken from a realistic perspective of what could actualy happen in our world. Most of it will unfold like a teen drama, with the X-Men growing into the people they are destined to become.
I doubt you'll have people leaving the Marvel RPG to join this one as this one is going to be COMPLETELY different. We won't be using any other heroes/villains that aren't asociated with the X-Men unless speacial GM permision is given, we won't be having giant world ending arcs, and most of the RPG will focus on individual character development. Anyone but the hardcore gamers may find it too slow for their tastes, but the intent is to focus more on the characters and less on the world coming to an end around them.
This is going to be a very, VERY different RPG than you have seen before. In all honesty there aren't that many X-Men to start out with, and I wouldn't want an overabundance our first go, so the roster will be, and probobly should be pretty small. It won't even near the size of Marvel, DC, either ULT, or One U. Its a smaller RPG for those that want to focus more on specific things and not world ending crisies always around the corner.