The world of Sosaria has changed beyond recognition following the defeat of the evil triad in previous Ultima games. Lord British, a benevolent monarch, has unified the people and proclaimed the Eight Virtues (Honesty, Compassion, Valor, Justice, Sacrifice, Honor, Spirituality, and Humility) as the ideal everyone should strive for.
The player's goal is to become the Avatar, a spiritual leader who can access holy artifacts, descend into the Stygian Abyss, and access the Codex of Ultimate Wisdom. To achieve this, they must uphold the Eight Virtues by making morally conscious decisions and helping others. The game does not reward behavior such as backstabbing or picking up unwanted items, but instead focuses on becoming a better person.
Gameplay involves character creation through responses to morally ambiguous questions, which assign a class and starting location for the Avatar. The player can then explore Britannia in various ways, collecting items and reaching the highest level in all virtues. Combat takes place on separate top-down screens, and characters accumulate experience points and level up.
Additionally, Ultima IV introduces new gameplay features such as party members, spell-casting using reagents, puzzle rooms in dungeons, and upgraded graphics in the FM Towns version. The game's unique approach established its reputation as a true RPG, influencing the design philosophy of later installments.
Ultima IV Quest of the Avatar was released for the Commodore 64 in 1979 .