We tie up the last two loose ends and fulfill the prophesied Sacrifice...
Notes on other versions
The SNES port of Ultima 6 is a relatively faithful version, albeit with some instances of censorship in the dialog and imagery (Gargoyles no longer have horns and enemies are "defeated" rather than killed, for example) and a considerably more cumbersome interface owing to the game utilizing a controller instead of a mouse and keyboard. There are also no in-game character portraits owing to memory constraints, and the game lacks a character generation sequence at the beginning.
The Amiga and Atari ST ports are largely the same, albeit with worse visuals and music and shipping on numerous floppy disks which necessitated frequent swapping. The C64 version also utilizes a keyboard interface like the previous games and requires very frequent disc swapping (NPC dialog is stored on a separate disk from the game itself). Numerous items and spells and all of the music and sound effects (save for the intro) were also cut for space constraints.
There is also a Japan-exclusive FM Towns port that has some slightly nicer sounding music and a somewhat simplified dialog system (operating on learned keywords rather than typed ones) as well as being the only version of the game that features voiced dialog (with many characters being voiced by members of the development team themselves, including Richard Garriott as Lord British). The voiceovers are of rather poor quality, but it's a pretty nifty feature nonetheless.
Secret Cheater's Menu
Talk to Iolo and say the phrase "Spam" three times, followed by "Humbug." This will enable a hidden menu that allows you to set game flags, create items, edit your party members and view any NPC's stats and portrait.
Savage Empire and Martian Dreams still have the cheat menu in their code, but it cannot be accessed without modifying the game. Martian Dreams contains a subtle nod to it as well - ask Dr. Spector about Spam and he'll reply that he enjoys eating it.
Other cheat/debug functions
All done by holding down ALT and typing the appropriate combination of numbers on the keypad.
Alt-213 - Shows an overhead view of your surroundings as if you had used a gem, and displays a number in the format KK TTTT XXYYZZ. KK is your karma level, TTTT is the current time of day, and XXYYZZ is your party's current coordinates in hexadecimal.
Alt-214 - Brings up a prompt (in Gargish text) asking for X, Y and Z coordinates (in hexadecimal). Whatever you input, your party will immediately teleport there.
Alt-215 - Advances time by one hour.