The Black Gate introduces the Guardian, an evil interdimensional being bent on conquering Britannia. Listen to his voice if you have speech, he sounds like a cult leader. ;) Play on and find out how much he hates to lose in later Ultimas across three different worlds. The Black Gate is also the first Ultima to feature ritual magic, with the possible exception of the end of Ultima VI.
The Fellowship: The Fellowship is something new in Britannia. Ask anybody and they'll tell you it deviates from the Virtues. If you're familiar with Britannia, you'll already know that's not good. You will have to find the truth out about this organization.
Just about all the cool secrets and junk have been discovered by somebody, but... Here's what I know:
Trinsic cheat room: A load of loot and teleporters. Treasure and quest items. Check it out by stacking crates into a makeshift staircase and climb onto the roof of the blacksmith's shop in the southwest corner of town, then walk behind the chimney. Most of the crates you can get in the shop itself, but you'll need to find a couple others. I suggest the tiny dwelling where the path turns north from the shop. Bring up your inventory screen to keep your virtue and grab the chests.
In some caverns north of Britain which I guess to be an extension of Despise, I wandered around and found some "love arrows." I'm not sure what special power they possess, but it's cool to go get them and they can't be made. (except with the cheat menu)
ItemsThe Forge of Virtue
Newer video cards with the Riva chipsets lock up whenever there's an earthquake. Earthquakes occur with the Forge of Virtue, and when a cyclops walks. Download this file to fix the problem. Also works with Serpent Isle.