Life's Blood and Condition

[Water Bob]

What happens if an attack takes you from, say, 9 HP right to -1? Do you take a wound then, too? Or do you proceed right to the Unconscious and Dying stage?

Just go to the Unconscious and Dying stage.

Are you envisioning a sort of table that lays this stuff out, that you roll against (like a Rolemaster chart), or is it supposed to be more freeform?

Freeform.

What limits do you have in mind for the ... mechanical power? ... of such wounds? E.g., how strong an effect can a wound have and how do you know when to apply it? Permanent blindness? Nausea for 1dX+Y rounds?

I'm thinking more hindrance than anything permanent, especially for non-criticals. Flavor. Wounds that puss up. Bleeding and maybe some hit point loss. A -2 modifier. Speed reduced. Scars after the wound heals.

Maybe steal the ideas from the "conditions" list, making someone deaf, or staggered, or stunned, or something like that.

Criticals would be a bit more serious. Maybe break an arm or have a body part useless.

Failed Massive Damage saves would count as a critical.



What happens depends on the description of the combat. If a PC comes in low, bent at the waist, almost crouched, with the point of his sword, and his enemy hits him, reducing him to 3 HP, then chances are the PC got hit in the head or shoulders.

Examples...

A dodging character who is hit and reduced to 4- HP may twist his ankle and be at half speed for a time.

A shield-parrying character who is hit and reduced to the "zone" might have his shield struck so hard in an "off" place of its surface that the top of the thing tilts back and breaks his nose. Blood runs down. Character is stunned for one round and maybe has blurry vision for 1d4 rounds CON check vs. the damage isn't made.

Stuff like that.

All critical hits?

Depends on the DM. Personally, I think not. I like giving checks to avoid. Like in the OP, there was a DEX check vs the damage to avoid dropping the weapon, and there was a CON check vs the damage to give the DM an idea to go "hard" or "soft" on the wound.

 

[Thanael]

The wound point/vitality system from UA does something like this:

Vitality Points

Vitality points are a measure of a character's ability to turn a direct hit into a graze or a glancing blow with no serious consequences. Like hit points in the standard d20 rules, vitality points go up with level, giving high-level characters more ability to shrug off attacks. Most types of damage reduce vitality points.

Characters gain vitality points as they gain levels. Just as with hit points in the standard d20 rules, at each level a character rolls a vitality die and adds his Constitution modifier, adding the total to his vitality point total. (And, just as with hit points, a character always gains at least 1 vitality point per level, regardless of his roll or Constitution modifier.) A 1st-level character gets the maximum vitality die result rather than rolling, as shown on Table 4-6 below.


Wound Points

Wound points measure how much true physical damage a character can withstand. Damage reduces wound points only after all vitality points are gone, or when a character is struck by a critical hit. A character has a number of wound points equal to her current Constitution score.


[...]

The first time a character takes wound damage - even a single point - he becomes fatigued. A fatigued character can't run or charge and takes a -2 penalty to Strength and Dexterity until he has rested for 8 hours (or until the wound damage is healed, if that occurs first). Additional wound damage doesn't make the character exhausted.

In addition, any time an attack deals wound damage to a character, he must succeed on a Fortitude saving thow (DC 5 + number of wound points lost from the attack) or be stunned for 1d4 rounds. (During that time, any other character can take a standard action to help the stunned character recover; doing so ends the stunned condition.)

 

[Tharkon]

The things that first came to mind with me (minus those answered already) were this:
Wouldn't all these extra checks (two extra rolls in your example situation) severely reduce the speed of gameplay?
What happens if a character ends up dying, stabilizes and regains consciousness?
And I read something about a failed massive damage save... failing those saves usually results in dead, so no need for any further penalties there.

In addition to the VP/WP system of UA there is also a critical hits table I got somewhere, not sure what book it's form but you roll a D% and then based on if the weapon is piercing, slashing or crushing you and the result of the roll you hit some body part causing some harm to your opponent.

Examples are: 100%, slashing: You decapitate your opponent. Death.
70%, piercing: You punctured the muscles of your opponent's hand. -1 to attack.
76%, crushing: You broke your opponent's knee. 1/4 move speed.

This can end battles quickly though, since any attack may result in death due to decapitating, fractured skulls or pierced hearts. It is also accompanied with a fumbled table to use for natural 1's on attack rolls.
Together the two can cause disastrous results, like rolling rolling 97% on the fumble, which is Big Liability: You hit an ally with a critical hit. And then rolling a 94% on the critical hit table piercing your allies throat, killing them.
It could also cause some impossible results like hitting your own hands.

It's a bit much, but it definitely gives flavor, so thought you might find it interesting.

Either way, on the topic of basing it on hp, not critical hits. I'd vote in favor of the 50%, 25% stuff. I once used to keep all hit points hidden from my players, including their own, and just tell them percentages, since that would be how they would feel or observe others. As a result clerics were as likely to heal a character with 5/10 hp as they were to heal a character with 10/20 hp. Since under this ruling they would both look just as injured, although the cleric would know how effective his healing was, and possibly remember it for the future. It also was not unlikely to assume that a mage that looked as injured as a barbarian probably was less likely to survive. The barbarian may be just as injured, but he's a tough guy, he can deal with it.

I think there is some house rule in a book somewhere (I thought PHB, but can't find it in the 3.5 version so it might be 3.0) that causes you to be staggered for 1 round after being hit 50% of your current hit points in one round.