Ultima VIII: Pagan

I can't believe it's not Ultima!

Ending Test
Create a file in the STATIC directory called I81B4U83.ICU with anything in it. Now there will be two new options in the Avatar's diary - one for viewing the ending sequence, and one for seeing the Developer Quotes.

Debug Mode
Ultima VIII continues the series tradition of having monstrously comprehensive cheat modes.

Crack open GAMEDAT/AVATAR.DAT in a hex editor and change 2A to 01, and 2B to 01.

F8 Menu
Press F8 at any time to bring up this buggy, buggy menu.

Button Commands
Press these buttons at any time during play to toggle them. Or you can activate them in the Toggles corner of the F8 Menu.

Hackmover (H Key)
Pick up anything. You can even stuff bits of the environment in your inventory! Can't carry around NPCs, though. But you can kill them by repeatedly picking them up and dropping them from a height.

Power Avatar (P Key)
God Mode by any other name.

Footpads (F Key)
Displays a grid over the gameworld, presumably related to collision.

Egg Bounds (E Key)
Displays egg boundaries. Duh.

Avatar Menu
Once debug mode is enabled, opening this menu is pretty easy. Just left-click the Avatar. A voice will shout "Cheater!" and laugh at you, and the menu will open.

Demo
Skip to any "cutscene" sequence in the game.

Spell Book
Lets you cast any spell in the game.

Information
Brings up a crosshair. Upon clicking an NPC you'll be given information on their location and current animation.

Enemy Caster
Brings up a crosshair and asks for a Spell Caster that must be a sorcerer and not the Avatar.

Time
The avatar tells you the time.

Key
The avatar says "You now have the key."

Staff
The avatar says "You have returned the staff."

Call Guards
Brings up a crosshair. Upon clicking an NPC, you'll be given various options to decide what you did. Once they pass, the NPC you clicked will call for a guard, and Beren will show up and judge the shit out of you.

Blow Up!
Does exactly what you think.

Kill Me
Brings up a crosshair. Upon clicking an NPC, they will be dealt untold amounts of damage, usually killing them unless they're immortal for plot purposes.

EndGame
Lets you spawn Blackrock Fragments or Energised Fragments.

Jump Ahead
Brings up a list of cryptically named options. Some spawn items, while others just make the Avatar say "Bzzzzt! Thank you for playing."