Cheating in Ultima Underworld

Ultima Underworld has a few available cheats.

The Endless Potion
This is the best-known oversight. Breaking a potion by attacking it with some nasty spells, turns it into a pile of garbage. However, the garbage still has the properties of the potion and will never run out! Especially useful with healing and mana potions.

Open the Door
Should a locked door be annoying, use "Dispel Rune". Despite an error message, all locks are removed.

Enternal Light
A weakness in the programming of the game is, how light is managed. If the darkness becomes annoying, just remove the shades.dat from the data-directory, and all darkness is removed, making lightsources a thing of the past.

Item Duplication
There is a surprisingly simple trick to duplicate items.

First, save your game while you have the items in question in your inventory. Next, put the items you want duplicated on the ground in front of you. After that is done, save on a different save slot. Now copy the PLAYER.DAT from the first save into the save directory of the second save. Once you load the second save, you suddenly have the items in your inventory and on the ground in front of you.

The explanation is simple: Items in your inventory, unlike the rest of the game world, are saved in the PLAYER.DAT, meaning that transplanting a player is trivial.

Hex-Editing for Stats
The PLAYER.DAT of each save game can be manipulated in order to ramp up the stats significantly. Bytes 10 to 3F have to be set onto FF and the bytes 40 to 4F onto 64 in order to get a significant boost for the player stats and abilities.