I was playing through Cyndassa's quest the other day, and looked at the UESP's page on it - which mentioned there's an alternate path (with the correct quest file fixes) that allows one to finish it without killing the quest target. That got me thinking, and I realised soon after that (if my memory serves; there aren't too many main quests so I think I remembered them all) that was the only one of the main quests that requires the player to actually kill anyone themselves - which means, if that one can be gotten around, it should be technically possible to win the game that way (only having one certain character killed by someone else, since he has to die at least some way). Obviously, it would be very difficult, but possible. Once I think up a good character design that can support that most easily, I might give this a try. I suspect that it would involve [a] Use of the languages to pacify the relevant (often dangerous) enemies (I'm not entirely sure this works, but from what experience I have it does seem to to some extent), [b] stealth to delay the rest noticing as long as possible, [c] RUNNING LIKE MAD if the first two don't work and [d] plenty of magic resistance. I do intend to wear armour, but obviously not carry weapons, and the "forbidden weaponry" disadvantages do seem to add up to enough to take a useful advantage or two along with a good number of magic points (for defensive, healing, and utility magic of course).
Any ideas, tips, or problems I may have overlooked are, of course, quite welcome.