Cheating in Ultima IV

Ultima IV has surprisingly few ways to cheat the program, yet some exploits are present.

The Status-Trick
This cheat takes advantage of the way that character's status work. In the game, enemies that put your characters to sleep (like Reapers and Balrons) can be neutralized by just having a character being poisoned. The game engine can only handle one status ailment (asleep, poisoned, dead) at a time, so a poisoned character can never fall asleep. Since poison is not much of a problem inside of dungeons, creating a poison field and poisoning characters before entering rooms with sleep-casting monsters will protect them from the sleep spells. Of course, Cure spells are required after the battle is done to remove the poison.

Money Through Mystics
Just like in Ultima III with the Exotics, it is possible in Ultima IV to find and sell the Mystic Armour and Mystic Arms repeatedly for money. However, it is harder than with Exotics, since you first need to be an 8-part Avatar before it is possible to find them in the first place.

Passage of the Moons
Normally, waiting on the world map for the right moon phase to open a moongate causes time to pass. This in turn makes you use up food, which is quite expensive, especially in the beginning of the game. However, if you push Z in order to read the stats, while time is stopped, the moons continue changing phases. This means that you can look at the stats until the right phase is there and then enter the gate, to save food and avoid conflicts.

Unlimited Nightshade and Mandrake Root
Normally Nightshade and Mandrake Root are difficult to come by because they can only be harvested when both moons are in the new phase. The current moon phase is not part of the save file, so every time one launches the game the clock resets back to new-new. This meas one can harvest either reagent until Felucca shifts, save, exit, reload, and then continue to harvest with only minimal delay. This is markedly faster than the previous Ztats trick.

Chests are Forever
Chests that are dropped by monsters stay on the overworld map forever. This can be used in creative ways, such as defeating monsters on swamp patches and then letting the chest stay there in order to be able to walk over the swamp without risking getting poisoned by it. This technique is especially useful when harvesting Mandrake Root, or marking the specific location of or a path to Nightshade.

Stats the Easy Way
There is a way to raise the stats very quickly for which you need at least one Xit spell. Then, enter the ladder in Castle Britannia down into dungeon Hythloth and immediately cast Xit to leave the dungeon. Entering from the surface, you just have to turn left to find a magic orb that raises all three stats. These regenerate each time you leave a dungeon and since this one is right next to the entrance, you can quickly raise your stats to the maximum by using it, leaving Hythloth, and then entering again.

The only difficulty is, that anyone below level 7 gets killed by touching the orb, so either have lots of Resurrect spells at hand, have the last man standing cast Gate Travel to return to Lord British for revival, or simply kamikaze and accept the loss of equipment and experience.