Ultima III

"I challenge you to name one other game where you can play a Transsexual Ewok Jester."

—Spoony: Ultima Retrospective

Ultima III is the first Ultima that was published by Origin. First released in 1983, finally quests and dungeons' started fitting together better and with more explanation. The game style would later inspire games such as Final Fantasy and Dragon Quest.

The Stranger killed the Big Bads of the previous two games, Mondain and Minax; but the waves and waves of monsters keep coming. They're organized; they're taking orders from someone or some thing, but nobody knows what. A "remnant" left over from the times of Mondain and Minax has survived. Did they have a child? Did they have some kind of demon servant that was overlooked? Was something left from all of that Schizo-Tech from mucking around with Time Travel? Yes.

In the midst of this, an Isle of Fire has arisen in the ocean. Some people have claimed that there is a castle in the middle, but the only way into the island is blocked by the Immortal Earth Serpent that can not be moved.

This Evil has a name. One of the ships that got too close to the Isle of Fire was found drifting offshore with its crew missing and a word written in blood on the deck. Exodus.

Tropes used in Ultima III include:

Beneath the Earth: The Underworld (referred to as Ambrosia) first appeared in this installment.
Black and White Magic: Magic Power and Will Power, respectively, which the different classes can use to various extents. Note that this is the only Ultima game with this split.
Covers Always Lie: The cover of Ultima III showed this demon looking thing that is presumably Exodus. The truth was a bit more complicated.
- Although via Retcon later in Ultima VI, it is revealed that it was Exodus too. Just a different part of it. The expansion of Ultima VII went into even more detail.
Dungeon: You actually have to enter most of them now; usually to get "Marks" which grant special abilities or get past a Broken Bridge.
Everything Trying to Kill You: In Exodus' lair, floor panels actually attack you, as does the the grass outside! In his interview with Spoony, Richard Garriott explains that this was because he had run out of space on the disk by this point, and realized that turning the floor and grass tiles into enemies actually made for a very difficult, strategically demanding battle worthy of the story's endgame.
Moral Dissonance: A minor case, but complaints about this inspired the next game's Karma Meter.
Names to Run Away From Really Fast: Exodus certain sounds scary. Never mind it's just a fancy way of saying "to leave".
Ninja Pirate Zombie Robot: Exodus turns out to be a computer that Mondain and Minax used to coordinate their power. Later games state that it's a demon/computer hybrid, and that the demon part "was elsewhere" when the Stranger crashed the server.
Schizo-Tech: Not nearly as oddly mixed as the first two games, but it is revealed that Exodus is a computer.
Sequence Breaking: The most powerful weapons and armor in the entire game are available as soon as you get a ship, and you know that you have to special command: dig on the tiny islands just off the coast. They're free.
Spoony Bard: Who found any reason to play as an alchemist or illusionist? Any?
Sword of Plot Advancement: The "Exotic" Weapons and Armor are the only things that work in Exodus's Castle. But even they don't work against Exodus.
Time Travel: In a different way from the previous two games. You are not the one who does it, but rather the "Time Lord" (no, not that one) gives you instructions on how to use the Cards which are revealed to be punch cards.
Weaksauce Weakness: Villainous example: the Undead spell instantly kills the undead, and Dispel instantly kills orcs (both weaknesses no longer exist in later games, "Turn Undead" merely causes them to flee, and Orcs apparently stabilize).
A Winner Is You: "Report Thy Victory!"