In Dungeon Master, what is the alternate ending that I have heard about?

Right after combining the Firestaff and the Power Gem on level 13, do not walk with it through the door. Rather throw the Firestaff through the door, take it back and go back to the entrance of the dungeon on level 00. The door will open and you will see the alternate ending. For more information, look at the notes on Dungeon Master Level 00 and Dungeon Master Level 13 pages.