Ultima IV: Quest of the Avatar, first released in 1985 for the Apple II, is the fourth in the series of Ultima role-playing video games. It is the first in the "Age of Enlightenment" trilogy, shifting the series from the hack and slash, dungeon crawl gameplay of its "Age of Darkness" predecessors towards an ethically-nuanced, story-driven approach. In 1996 Computer Gaming World named Ultima IV as #2 on its Best Games of All Time list on the PC. Designer Richard Garriott considers this game to be among his favorites from the Ultima series.

Instead of simply choosing stats to assign points to as in the first three Ultima games, you are instead asked various ethical dilemmas by a Gypsy using remotely tarot-like cards of the eight virtues. These situations do not have one correct resolution; rather, players must rank the eight virtues and whichever stands as their highest priority determines the type of character they will play. For example, choosing Compassion makes you a Bard, Honor a Paladin, Sacrifice a Tinker, and so on. This was also the first Ultima game where you had to play as a human, eliminating other races such as the elves, dwarves, and "bobbits" found in previous games altogether (however, even in the first three Ultimas where they could be chosen as player characters, there were never any non-player characters of those non-human races).

Although each profession embodies a particular virtue, to become an Avatar the player must achieve enlightenment in all eight virtues. Enlightenment in the virtues is achieved through the player's actions as well as through meditation at shrines. Shrines to each of the virtues are scattered about Britannia, each requiring the player to possess the corresponding virtue's Rune before allowing entry. Through meditation and correctly repeating the virtue's Mantra one to three times at the shrine, the player gains insight and ultimately enlightenment in the virtue. A seer in Lord British's castle provides the player with feedback on their progress in the virtues.

Technically, the game was very similar to Ultima III: Exodus, although much larger. This was the first Ultima game to feature a real conversation system—whereas NPCs in the earlier parts would only give one canned answer when talked to, now players could interact with them by specifying a subject of conversation, the subject determined either by a standard set of questions (name, job, health) or by information gleaned from the previous answers, or from other characters. Many sub-quests were arranged around this.

Another addition were dungeon rooms, uniquely designed combat areas in the dungeons which supplemented the standard combat against randomly appearing enemies.

The world of Britannia was first introduced here in full, and the world map in the series did not greatly change any more from this point onward. The player may travel about Britannia by foot, on horseback, across the sea in a ship or by air in a "lighter than air device". Speed and ease of travel is affected by the mode of travel as well as terrain and wind.

Virtues

The eight virtues of the Avatar, their relationship to the three principles of Truth, Love and Courage and how the gameplay has been designed around them are as follows:

• Honesty: Truth
  When purchasing goods from blind merchants the player is required to enter the amount they actually wish to pay. Although the player has the option of paying less than the merchant has asked for, this will mark the player as dishonest. Stealing gold from chests owned by others (i.e. all chests found in towns, villages and castles) will also penalize the player. This Virtue is embodied by Mariah the Mage.
• Compassion: Love
  By using the Give conversation subject, a player can give beggars alms and in doing so demonstrate compassion. This Virtue is embodied by Iolo the Bard.
• Valor: Courage
  Valor is displayed by the player defeating enemies in combat and not fleeing in a cowardly fashion. This means that when retreat is necessary, the player should be the last party member to leave the field of battle. This Virtue is embodied by Geoffrey the Fighter.
• Justice: Truth and Love
  Not all of the hostile creatures in Britannia are evil and the player must avoid unprovoked attacks on those that are not. If attacked, he should resort to driving them away rather than killing them. Out of the eight virtues, this one requires the most finesse to embody and is a particularly good example of balancing ethical dilemmas. The player's party must stand their ground for Valor, yet drive their foes away without killing them. This Virtue is embodied by Jaana the Druid.
• Honor: Truth and Courage
  By completing quests (finding sacred items) and exploring dungeons the player demonstrates their honor. This Virtue is embodied by Dupre the Paladin.
• Sacrifice: Love and Courage
  If the player goes to a place of healing while in good health, the player can make a blood donation and sacrifice some health in doing so. This Virtue is embodied by Julia the Tinker. In the NES port she was replaced with a male character named Julius.
• Spirituality: Truth, Love and Courage
  Meditating at shrines, consulting the seer, and achieving enlightenment in the other virtues enhances the player's spirituality. This Virtue is embodied by Shamino the Ranger.
• Humility: None, though it is considered the root of all virtue.
  The player demonstrates their humility during conversations. A boastful response to a question results in a penalty, a humble response results in a bonus. This Virtue is embodied by Katrina the Shepherd.