I've always wanted Bethesda to include a quest in that could be extremely difficult and yet satisfying to accomplish.
We could solve a series of intense challenges through an underground complex to get to a unique worldspace below. Maybe they could include a unique treasure or two at the end, who knows?

I know there are similar quests to this, but what I'm talking about is an extremely laborious task that will tax every one of our emotions just to reach the end.

There's a game called Spelunky, in which you must acquire different and hard to reach items to access a unique place called The City of Gold, and from there there's even a harder to reach hell. It's painstaking, yet awesome in its right to behold. It's a lot of fun to see and just a pleasure in itself to reach.

This would not be the kind of task any one person could just undertake; it would take a skilled Skyrimmer to vanquish The Impossible Quest!

Some things I have yet to determine would be: what kinds of monsters are there, should one be able to simply save, and what could possibly be The Ultimate Prize?

There are probably some flaws to my evil plan, and some rejections as well, but feel free to comment, whether it be benign or malign.

That'll work only if it have a Dark Souls-like difficulty and if it's only accessible with the hardest difficulty this game can offer.

That would be pretty cool, lots of potions and reloads I assume?

Yes. There'd be a need to compensate.

i love the idea. perhaps an unlockable sort of thing ounce you reach the end.

You could script a dynamic dungeon to get around that. Look at how quickly a creature dies, how much health a player loses killing it, how many followers the player had, how many potion they are carrying and what the effect magnitudes are. The list goes on.

If they're not a high enough level, or they stacked the odds to greatly in their favor, or they're using the console to cheat, or they haven't run the dungeon trying enough times in a game, you just lead them back to the surface. One array of dungeons, many paths.

It's totally doable. A lot of work, but totally doable.