I don't think this was mentioned above: Ultima IV was released into the public domain by its creators, or perhaps put under an OS license I'm not sure which. The best port of it to modern operating systems is xu4:

http://xu4.sourceforge.net/

Yes, TOTALLY a ridiculous difficulty spike. I also got some weird bug that appeared to be related to this; eventually a number of ships, including two copies of KM's ship, appeared out of nowhere stuck against the perimeter of the A.