One thing skirmish games have, generally, are rules for checking if lost skirmishers are really dead. Oh sure, your archer/ork/barbarian hireling/apprentice wizard/familiar got killed in the battle, but are they really dead?
You go and roll on a table, or make another check, etc. to see if they're dead.
I think that in D&D/AD&D games, this might be a useful way to go. You "die" at -0 HP. Unless you get taken straight to complete death (-10 HP in AD&D, different scores in different variations and house rules), you're merely out of the fight (and the adventure.)
But you might not be dead.
An arbitrary random table might work. He's one that's cribbed from games like Frostgrave and others.
4-6 Lose 1 from any chosen attribute or from permanent HP total.
7-9 Badly Wounded: Temporarily reduce Movement to 75% of normal and HP to 75% of total.
10-12 Unconcious: Character was only unconscious. Reduce movement and max HP to 75% of total for the current adventure only.
13-18 Fine, fully recovers between adventures.
19 Unconscious - recovers to 1 HP immediately and is ready to continue adventuring.
20 Stunned - recovers to HP total prior to the final hit, and is ready to continue adventuring.
Alternatively, you can make it a targeted roll. Say, target is roll under your level + CON bonus:
Make with a 1: Recover after the immediate combat with 1 HP.
Make it: Recover after the adventure, fully.
Miss by 1-3: Movement and max HP are 75% normal for next adventure.
Miss by 4-6: Recover after the adventure, but wounded badly - lost 1 from any chosen attribute or from permanent HP total.
Miss by 7+: Dead!
Or just roll System Shock right then and there. Fail it? Dead. Succeed? Alive and needs to recover between sessions.
I haven't playtested these or fully explored the ideas, but I figured I'd get it out on my blog and see who can do more with it.