OK - thanks.

Regarding destructive testing - the IBM Black Team is/was legendary, isn't it?
I spent many years as a developer and IT manager, responsible (not only) for testing large and small systems through the whole testing cycle. The first testing experience beyond simple program testing I remember was when I was the manager of a development project, and one of my developers showed me, proudly, an input dialogue he had created. I simply hammered the keyboard blindly with my two fists - and the system fell over ... It's true, I learnt over and over again that most developers have scrouples to "hurt" their own system, their "baby", so-to-speak. I myself never felt this way.
Playing a computer game is a different story. It's about enjoying, not testing, and this means different things for different people. I think it's most important that we enjoy games in our own way and as much as possible - I'm sure you agree.

Yes, one can definitely climb or otherwise glitch one's way back into the level proper from on top of a segment. I never tried to get out-of-bounds on purpose (that I can remember), but it was not that uncommon an occurrence nonetheless. In instances where I didn't just fall all the way to the bottom of the void -- where the character becomes immobile and is stuck, short of either using one of the cheats which've been mentioned (which I doubt I knew about back when I was really into the game) or the recall spell (which my character didn't always have access to for any number of reasons) -- and instead landed on top of a lower dungeon segment, and where reloading a previous save might've cost me an hour or more of dungeon-delving progress, I was sometimes quite motivated to try to get back inside the level proper by any means I could. :)

In a word: immersion. Even knowing all the above, and even holding close to my heart the ideal of "save early, often, and in a different slot (almost) every time", sometimes I get engrossed in a game, and only realize that I haven't saved in three hours after the game has crashed or frozen, or I've gotten myself into a situation I can't get out of except by reloading. It happened to me 20+ years ago, it sometimes happens to me now, and it will probably happen 20 years hence, assuming I'm still in a condition to be able to play games -- and that there are still games that can draw me in as much as this one did 15-20 years ago.