I will start with the 1e mechanic, which reads:
When any creature is brought to 0 hit points (optionally as low as -3 hit points if from the same blow which brought the total to 0), it is unconscious. In each of the next succeeding rounds 1 additional (negative) point will be lost until -10 is reached and the creature dies. Such loss and death are caused from bleeding, shock, convulsions, non-respiration, and similar causes. It ceases immediately on any round a friendly creature administers aid to the unconscious one. Aid consists of binding wounds, starting respiration, administering a draught (spirits, healing potion, etc.), or otherwise doing whatever is necessary to restore life.
Any character brought to 0 (or fewer) hit points and then revived will remain in a coma for 1-6 turns. Thereafter, he or she must rest for a full week, minimum. He or she will be incapable of any activity other than that necessary to move slowly to a place of rest and eat and sleep when there. The character cannot attack, defend, cast spells, use magic devices, carry burdens, run, study, research, or do anything else. This is true even if cure spells and/or healing potions are given to him or her, although if a heal spell is bestowed the prohibition no longer applies.
The first thing I want to discuss in the indication that the felling blow could bring hit points “optionally as low as -3 hit points if from the same blow which brought the total to 0”. I see two possible interpretations of this. The first, and the one I always used, is that if the blow brought the PC to -4 hp or lower, the PC was automatically dead and this section did not apply. However, it could also be interpreted that no matter how severe the blow was, for the purposes of the rule the PC was always treated as starting at no lower than -3 hp. If anyone knows of an official ruling in this regard, please advise.
Assuming the PC is not outright killed, and is at somewhere between 0 and -3 hp, he then proceeds to bleed out at a rate of 1 hp per round until somebody uses healing magic on him, or binds his wounds. Binding wounds automatically stops the bleeding.
Thereafter, unless a heal spell is used, the PC is out of the fight, and cannot fight or cast spells for at least a week. He is, however, able to get out of the dungeon under his own power, although at a slowed pace.
There is one other point, which may seem evident but which is relevant to the 4e discussion later on. Since the rules appear to be silent on the matter, I assume that any healing that is applied is added to the negative hit point total. So if a character is at -6 hp and receives 3 points of healing from a cure light wounds spell, he will then be at -3 hp (although he has at least stopped bleeding).
I also assume that additional damage (from getting caught in a fireball, or opponents hacking at fallen bodies but not attempting a
coup de gras), are deducted from the negative hit point total, and can hasten the trip to -10.
The relevant elements of this mechanic are as follows:
- There may be a possibility of immediate death from the initial blow, if it takes the PC lower than -3 hit points. Otherwise the “Zero hit point” mechanic is in effect.
- If he reaches -10 hit points, he dies
- The rate of bleeding out is predictable, therefore the round of death is predictable
- A bleeding character has a minimum of 7 rounds before he dies
- The binding of wounds automatically succeeds
- Points of healing are added to the negative hit point total
- Unless a heal spell is cast, the character is out of the fight
- Unless a heal spell is cast, the character cannot engage in any further adventuring for at least a week
- The character is able to leave the dungeon and get to a place of rest under his own power
So, other than creating a safety net for characters, what does this mean for game play? Your character is involved in combat and sees one of your party members drop, what do you do about it? Well, nothing for at least 6 rounds, or until the battle is over, whichever comes first.
You likely know the fallen character’s exact hit point total, so you know exactly how long you have, so if he is at -1 hit points you know you have 8 rounds to administer first aid. Success in administering first aid is automatic, so there is no risk in waiting until the last minute (barring coup de gras, etc.). Scarring is possible if he hits -6, but this is purely cosmetic, and the rules do not suggest this results in a change to any ability score including charisma. The character is out of the fight regardless of what you do, so healing him early does not improve the tactical situation. The only incentive to stop the bleeding early is to shorten the number of days required to heal, which will probably be mitigated by cleric magic anyway.
So what if the DM conceals the fallen character’s hit point total? You still know you have a minimum of 6 rounds, and will delay taking any action until then. This is true even if the DM conceals the information as to whether the character died from the initial blow, since if he died, any expenditure of effort in stabilizing him is wasted.
Another impact is that magic will almost never be used to help a fallen character during a battle, short of a heal spell, because first aid requires the same actions, healing is expensive in potions or spell slots, and healing spells can be interrupted.
After the combat is over, the party can wait for the PC to wake up (1-6 turns) or carry him around with them. Once he is awake he can shuffle around under his own power. The party then has the choice of escorting him back to a place of safety to rest; bringing him along while they continue adventuring to which he is unable to contribute (essentially volunteering for an escort mission), which may well require carrying him; or going on without him and letting him take his chances with the wandering monster tables while he slowly makes his way to safety.
(From a simulationist perspective, I am not sure if the 1-6 turn timeframe is correct, I believe I have read that people who have been downed by non-fatal injuries usually only remain unconscious for a few minutes unless they enter a coma, in which case it is much longer.)
Thereafter he is out of commission for at least a week (longer if he is relying on natural healing), and the party has to decide whether to risk further adventuring without him, or stay at home and let the cleric speed up the natural healing process. This is one of many 1e mechanics that forces players to deal with down time, and to spend time in population centres. It may also have a certain simulationist appeal, if that is your preference.