Apparently, Ultima Online, Ultima Underworld, and Ultima VII were all on the table at some point:
Four games in the series sprung to Barnett's mind once that first decision was made, but two — Ultima Underworld and Ultima Online — were blackballed relatively quickly, due to the fact that remaking them would "cost a fortune." Only two games remained for BioWare Mythic to debate over: Ultima 4, and Ultima 7.
"Ultima 7 I really liked," Barnett explained. "It was the simulation Ultima. It was the one that had one-to-one scale, it's the one that had a weather system. Your own party, when you recruited them, they blew you up with their lightning spells. It was marvelous. You had the Black Gate, and you had the Guardian. It was great, but it was a simulation. And simulations are tough to code.
"Ultima 4 was the first grown-up Ultima," Barnett added. "That's the Ultima where we went, 'You know what? A fully-realized world, and great ideas, and have in it a moment of supreme clarity: It's about Virtues, it's about being a good person.' In my opinion, Ultima 4 is the birth of the great RPGs. And, I'm of the opinion that it needs to be revisited, because people really haven't done it. We've slipped back into, 'Oh, he needs to be a dragon, or he needs to be a demon, and everything needs to be covered in blood, and he has to have angst, and no one's allowed to be a good person.