I like the way that once you're in the dungeon, if your stamina runs out, you die. It does not matter how powerful you are. The green bar is a measure of how long you have left to live. If there are enemies nearby wherever you run, the green juice will run out and you will die. If you fall through a trap door, it might drop you 200 feet and you will die. If you wander a dungeon casually, you'll get lost and die. If you meet a lich and are not a walking antimagic fortress, you die. If you fall into water, you may sink; you swim slowly, because that's how it is with people (particularly armored people), and if you run out of breath, you die.

Daggerfall just has this menacing atmosphere to it that will never go away no matter what level you are, because you're always at risk. What would top it? Well not a 13 square mile map, for starters