Different gamers put different emotional investments into their characters. Some don't mind losing characters, because they just enjoy the Game itself. TPK? No problem. Roll 'em up, get it on!
Some, however, develop elaborate back stories and personalities for their characters, and the loss of their personal in-game avatar is traumatic. My girls for example, love elaborate characters, with intricate and complex backgrounds full of webs of intrigue and unique personality traits and family histories, etc... Such characters cannot simply be cast aside lightly.
Thus, I need ideas that facilitate keeping characters alive. This is treating the game like a heroic movie, which gives the lead character chances to escape what in harsh game terms should have been instant death. Think: Luke Skywalker knocked out by Sandpeople, but not killed, hung from the roof of the ice cave, but not eaten, dropped into pit to be eaten by monster, rather than directly executed, and so on.
Some of it became cliche and trite, think of Austin Power's take on 007's various escapes... "Why don't you just shoot him, numbnuts?" But in game terms, such devices are there to allow the characters to lose, yet not be eliminated, to be set back severely, yet keep the game fun and give them a second chance at success. So, how can we do this in the AD&D environment?
First of all, keep in mind, not all battles are to the death, or even to the pain***. The results of losing fights can vary considerably, depending on the monster faced, sentient or non-sentient, and the impetus for the fight in the first place.
Also, remember the importance of Charisma checks. Most of the time, sentient creatures will attempt to bluff and bully their way to domination. The word here is role-playing, you know, the RP in RPGs! Charisma scores and reaction tables play a big role here, so use them. Don't forget, the goal is to accomplish some task, acquire some object or reconoiter some information, not just slaughter everything. That is called Hack-and-Slash, which has its place, but that place is not foremost.
The simplest solution to losing a fight is always...
A) Highway Robbery!
Waking up in a lot of pain, stripped of all equipment and treasure. Returning to home base without weapons or rations will be quite an task, won't it? Used to thinking outside the box? I hope so...
When fighting sentient monsters, a battle loss might also result in...
B) Capture!
This could involve any number of end-points, which would create entire new adventuring hooks, and might depend on charisma checks as well. Some possibilities...
-The forced march.... Remember Frodo's capture and forced march deep into enemy territory? This may actually result in the advancement of the PCs progress. Can our heroes find a way to escape and continue their quest???
-Pressed to row aboard a pirate ship.... Nice fresh sea-air sounds fun, hope you can swim well, when the Kraken rips the ship in half...
-Saved for use as sacrafice to demon-gods in evil temple... Being well-fed and carefully groomed is just the beginning...
-Taken deep below ground and forced to dig for Drow at the end of a whip... Oh, shazzbot...
-Field laborer in foreign kingdom.... Too bad you spent so much time building up that physique, tough guy, how you gonna get that chain off your neck....
-House slave in some mad magician's castle... Sounds pretty interesting, doesn't it? What happens when your master loses control of the creatures he has been summoning/creating, or decides you are the perfect test subject for his new spell...
-Chained to a wall in an Orc dungeon... Better hope your family likes you enough to pay the ransom...
Non-sentient creatures will fight for territory or out of hunger. This brings up many different fight loss scenarios.
-Dropped off into the nursery... The little hatchlings need sustenance, don't they? Can our heroes ward off the little ankle-biters and get out of there before mommy comes back?
-Put in the storage box... The big nasties are busy feasting on the horses and NPCs, the heroes appear to be on the dessert menu...
Of course, the fight loss might be interrupted by...
C) Outside intervention!
--Priestly prayer has a certain percentage of being heard and answered... What is rule, 1% per level of the character, for getting some divine intervention?
- Competing monster.... The sounds of battle attract many onlookers, some of which might be hostile to the attacking monster, perhaps trying to muscle in on the food, or take advantage of the weakened creature... "The enemy of my enemy is my friend" would seem to apply here, perhaps giving the heroes a precious few seconds to escape or hide. Of course, this might also lead to an "Out of the Frying Pan Into the Fire" scenario...
--Helpful monsters... The MM is full of powerful creatures who love to intervene on behalf of people supporting their alignment. "The heat from the dragon's breath sears your skin as you dive behind the rock for cover. The huge beast rises to its full height above you as you raise your broken sword in one last gesture of defiance. Suddenly a powerful sound rings out, like a giant lion's roar, and the earth shakes as huge flat feet smash into the ground behind you. You turn to see what appears to be a giant lion, with pegasus wings and a man's bearded head, which then leaps over you, clawing savagely at the dragon's head, driving it back from you and your almost-broken companions...."
See: Lammasu, Shedu, Hollyphant, Ki-rin, Deva, Planetar, Agathion, Moon Dog, others....
-Helpful humans, demi-humans, semi-humans to the rescue... Hearing the sounds of battle, some locals decide to intervene, to thwart their ancient foe, or to gain some allies, or some appreciation money, or out of sheer goodness.... Could be a wandering adventurer, a band of elves, a troop of centaurs, etc. Wheew, good thing they arrived right in the nick of time....
Anyway, keep a few of these options available and in-mind, to avoid any unwanted TPK's that your dice might lead you into.
*** "to the pain" :
Prince Humperdinck: First things first, to the death.
Westley: No. To the pain.
Prince Humperdinck: I don't think I'm quite familiar with that phrase.
Westley: I'll explain and I'll use small words so that you'll be sure to understand, you warthog faced buffoon.
Prince Humperdinck: That may be the first time in my life a man has dared insult me.
Westley: It won't be the last. To the pain means the first thing you will lose will be your feet below the ankles. Then your hands at the wrists. Next your nose.
Prince Humperdinck: And then my tongue I suppose, I killed you too quickly the last time. A mistake I don't mean to duplicate tonight.
Westley: I wasn't finished. The next thing you will lose will be your left eye followed by your right.
Prince Humperdinck: And then my ears, I understand let's get on with it.
Westley: WRONG. Your ears you keep and I'll tell you why. So that every shriek of every child at seeing your hideousness will be yours to cherish. Every babe that weeps at your approach, every woman who cries out, "Dear God! What is that thing," will echo in your perfect ears. That is what to the pain means. It means I leave you in anguish, wallowing in freakish misery forever.