What if Ur, like Pangea, were a supercontinent (aka *Urkontinent*), whole for a time but bound to drift apart? I just had this idea that sometime in the future there might be a Rook attack so devastating that it cleaved the world into separate continents and islands with ocean between them.
This would, of course, be a gap that subways couldn't bridge, opening the way for BOATS! I know I'd love to be an adventurous ship captain, ferrying Glitchen from island to island to seek their fortune.