The fourth game in the now well-established Ultima series featured an improved version of the Ultima IV engine, with color graphics and better character interaction (you could now have actual conversations with NPCs). But what really makes Ultima IV shine is its radical departure from any other RPG made before or since in terms of the story and goal.

Instead of building up your character by any means possible in order to face the Ultimate Evil in a big bang up showdown, in Ultima IV you were trying to become the Avatar, a role model of sorts for the people of the land. This meant upholding the "eight virtues" and basically trying to become a better person. In most RPGs you chose to be a just/nice hero because the people you'd help would usually provide you with some nice equipment for your services, but in Ultima IV you helped people not for a reward or to advance the plot but simply because it was the "right thing to do". The game actually frowns on behavior that was typical of most other RPGs, such as backstabbing fleeing monsters or picking up everything that wasn't nailed down even if it didn't belong to you. The game keeps track of all your actions, so if you went about killing and looting like in most RPGs, you'd never finish the game.

This VERY different approach to the game's ultimate goal is what makes Ultima IV famous so many years later, and became the sort of design philosophy that made all the following Ultimas so unique in their genre.

Of course, the game still has plenty of traditional RPG elements such as dungeons to explore and hostile monsters to kill, as well as a typical final "Holy Grail" type quest where you had to find the Codex of Ultimate Wisdom to complete your transformation into Avatarhood.

After the defeat of each of the user of the triad of evil in the previous three Ultima games, the world of Sosaria underwent some radical changes in geography: three quarters of the world disappeared, continents rose and sank, and new cities were built to replace the ones that were lost. Eventually the world, now unified in Lord British's rule, was renamed Britannia. Lord British felt the people lacked purpose after their great struggles against the triad were over, and he was concerned with their spiritual well-being in this unfamiliar new age of relative peace, so he proclaimed the Quest of the Avatar: He needed someone to step forth and become the shining example for others to follow.