It's been a year since you defeated the Guardian, and Lord British has invited you to celebrate the reconstruction of Britannia. However, the next morning, Castle Brittania has been covered with a magical black dome by the Guardian. You are the Avatar, and must destroy each of the layers of rock in Britannia's Underworld to restore peace.
The game is very fun to play, and is very similar to UW1. If you've played the first one (availiable on Abandonia) then I reccomend you play this one.
The only thing I could find wrong with this game was the interface. Unlike UW1, the buttons are at the bottom of the screen. If you're like me, and have played UW1 every year since you got it (pathetic, I know), you might find it a bit annoying.
Overall, it's a brilliant RPG that should be in anyone's collection.
You'll have to play it under DosBox.
Part of the Ultima Series