(My long, rambling description of said rules can be found here: http://lizardmandiaries.blogspot.com.au/2013/09/house-rules-for-death-or-near-death-in.html)
I have two major issues with these rules. Firstly, I was I was never applying the "negative value of HP" to the CON check/saves that people had to make. It always felt too mean/messy to ask that of a dying player, so I would always revert to just asking for unaltered CON saves. Secondly, I was always a loose with the rules, and the dying process seemed to be conducted in a slightly different way each time.
Death requires strict, simple rules!
The new rule is based on Save Vs. Death (which should work out to be the same as Save Vs. Poison in your OSR rules of choice).
Dying:
If a character is damaged as to be on 0 or less Hit Points they are dying.
Each round they must make a Save Vs. Death to see if their injuries cause them further damage. If they fail this Save they take d6 extra points of damage.
Each subsequent round the dying character is left without medical aid they continue to attempt Save Vs. Death at a cumulative penalty of 2 (ie, a penalty of 2, then 4, then 6, etc).
Additionally the damage caused by a failed Save increases by 1 die type each round (ie, d6,d8,d10, etc).
A character going below the negative value of their Hit Points dies.
Characters may attempt to stabilize the dying character by spending their turn tending to them, and making a successful WIS check (apply appropriate situation modifiers to the roll). Being stabilized by another character requires the dying character to make an additional Save Vs Death (the cumulative penalty is ignored). If failed they take the appropriate die worth of damage and must attempt to the Save Vs. Death each round until they are successful and are then unconscious but stabilized. The cumulative Save attempt penalty is not applied when another character is attempting to stabilize a dying character. Each round of stabilization attempt requires the non-dying character to make a successful WIS check otherwise the cumulative save penalty will apply. .
Characters successfully passing 3 Save Vs. Death rolls (including cumulative penalties) stabilizes themselves through sheer force of will to live.
Stabilized means the character is not in immediate danger of dying from bleeding/internal injuries, but they are still unconscious and at 0 or less HP. They will not heal naturally.
Each day a Stabilized but unconscious character must make a Save Vs. Death. If they fail they are once again dying (repeat the above process). If they make the save, they are in a stable (albeit comatose) condition for another 24 hours.
Thoughts:
The 3 Save Vs. Death rolls represent 30 seconds. This seems like a decent amount of time for a body to decide if it's going to stop working and die, or keep on trucking as best it can.
A dead party member doesn't present much in the way of choices for the other party members (other than deciding if it's time to run or not). A dying party member does: Will the parties' resources be rerouted to stabilizing their dying comrade? Or do they just pray and hope the unconcsious, bleeding dwarf pulls through on their own accord and get to them once the fighting is over?
Dwarfs and Halflings (in Labyrinth Lord) are appreciably harder to kill using this system. At level 1 a Dwarf or Halfing has 20% less chance of dying than a Fighter. I like that.
High level adventurers become pretty hard to kill. Hubris coupled with the cumulatively save penalty and the ever growing dice values of the death damage will get to them eventually though.
I like this rule because it uses Saves. I want to use Saves more often in my games.
