Morrowind - Leave the level

First of all you need to use the fortify skill + soul trap spell trick to get your speed level to a few thousand. If you don't know how to do this read this:

buy soul trap from the mages guild and a fortify attribute spell (the only one I can think of now is jack of trades from sayda neen) then make a spell with fortify speed any amount of points for 2 seconds on self and soul trap on target. Then cast the spell while looking at the ground and you will get speed points that wont go away.

Then get your speed to a thousand or so and run towards a door, if done correctly you will run through the door after a few tries and be outside of the level.

note that you may fall to your death while exploring the outside of the level