Aartha seems to have been found by one user at the assembler forum:https://assemblergames.com/threads/agartha-dreamcast.66487/. uts very early but its running and interactive.Its nice to see how cool it would have been.Dreamcast junk yard talks more about it http://www.thedreamcastjunkyard.co.uk/2017/08/playable-demo-of-cancelled-dreamcast.html