Yeah I have no problem with that, it is just a game after all and I'd rather people get kicks out of being cruel in a game than in real life. I just don't want to be creeped out by nearly dead people begging for mercy all the time. If you could actually engage in non-mortal combat and let people go I'd love that, but at some point it gets a tad ridiculous as well.
Like many other things that end up being mods, it wouldn't work for everyone the same way. But I think it's possible, and a good idea.
I'm imagining a constant cycle of fighting enemies and then allowing them to run off. It sounds kind of ridiculous, granted a single hero doing so much on their own isn't exactly logical either now that I think about it.
Variety in enemy behavior helps. For example, you come across one particular group of outlaws roughing up an unarmed, or just simply outmatched, commoner. You step in, being the righteous type, and quite handy with some non-lethal spell-casting, and teach them a lesson. Some of them get angry at you enough to force you to hurt them more than you intended, some of them take the hint and run off, and at least one challenges you to mortal combat, in which case leads you to making the choice of whether slaying them is just.
Later on, you stumble into a ruin filled with some other outlaws, who are way more powerful than you, and you are the one who runs away, while they don't even bother chasing you because they're too busy pilfering artifacts. Or fighting over them.
It wouldn't all be based on level so much as AI, which I'm not sure how difficult that is to work with, but hey, it's just an idea.
Lol, wonder if you could get a reputation for not sparing enemies. Then they fear you more!
Or hate you, because you're such an evil bastard.
Or if you spare too many they quit fighting soon as their wounded and beg, knowing that you are too soft to finish them. Then they laugh and plot against you as they wander away...
Yes, the old Batman-doesn't-kill-let's-take-advantage problem.