Cheating in Ultima III

Ultima III was the first time in the series, that rampant cheating was made available, although it does not have any kind of internal cheating options. This is entirely due to oversights in programming.

Exotics: Armor and Weapons
While I'm not sure if this a bug or actually count it as a cheat, I'll not hide it from you all. After you dug up the Exotic Armor and Weapons, you can quickly cashing in by selling all of them and returning to the same hiding place for more.

Money and Equipment galore
Ultima III is using a character creation similar to the D&D games, and like in these games, it can be misused to great effect.

You'll see when creating a character, that they always start with 150 gold and 150 food. All characters are in a roster that can be accessed at the start of the game and the attributes of each character are saved when saving the game. This system can be misused in a big way in order to make the start of the game very easy. To do so, at first just create one character you want to keep, and three dummy characters, whose stats and class are irrelevant. Then start the game and transfer all the gold and food to the permanent character. Save the game and restart it. You can now delete the dummy characters, but keep all what was theirs on your permanent character.

You can do so as often as you please, even store the permanent characters in the roster until the four permenent characters you want are well equipped with gold and food. This of course also works with transferred equipment.

Easy Entrance to Exodus Castle
The way that pirate ships are spawned in Ultima III after reaching level 5 can be misused.

Entering the moongate that leads to the Isle of Fire often gives the chance that a pirate ship is spawned in the small pool of water behind the Great Earth Serpent, thus allowing easy access to the castle and making the journey into the Dungeon of the Snake no longer needed. The best thing is, that the ship is safe from the whirlpool behind the serpent.

Free Horses
Normally, horses cost 800 gold pieces. They can be found for free in Old Fawn, but since it is on an island and horses can't board ships, it normally is useless. However, using three ships as a bridge between the island and the mainland allows riding the horses onto the mainland and parking them there. This can be done as often as wished, as long as the ships aren't eaten up by the wirlpool.

Shortcut to the Endgame
The NES port has a bug that can short-circuit the plot. The Four Cards aren't actually needed; it is enough to make it to Exodus himself. This can be done the quick way just by misusing the Moongate to the Isle of Fire until a pirate ship spawns in the small pond behind the snake, enabling access to the castle without the need for the Mark of Snakes. Once Exodus has been reached, the game will behave as if the player already has all four cards, even if they really don't.