Worlds of Hurt

More confessions: I'm not, nor have I ever been, a fan of hit points. While I agree that they’re an easy way to gauge combat stamina and track damage, they fail me on two counts:

1. You can’t do one-shot kills—when a foe has more than 1 HD, you usually need multiple hits to bring him down, and
2. You can’t simulate performance degradation—meaning you’re just as effective at 1hp as you are at 50hp

Yet, it's hard to beat hit points for convenience and familiarity. I mean, everybody knows what a hit point is, and pretty much every OSR resource is going to use them. So here’s a possible solution to the two issues above, with the added benefit of being able to use existing S&W stats without modification. [1]

We'll start by keeping hit dice and hit points. When an attack hits, roll damage normally and subtract from the target's hit point total. However, when an attack is a critical hit (see below) or when a combatant reaches zero hit points, the defender rolls on the Hit Location table to see what happens. [2]

Critical Hits

A critical hit occurs when an unmodified attack roll result falls within the attacker’s critical range, which is 20 minus his class-based to-hit bonus. For example, a 4th-level fighter with a to-hit bonus of +2 has a critical range of 18-20. Thus, if his d20 attack roll shows a natural 18, 19, or 20, and the attack succeeds, it’s a critical hit. A monster's critical range is calculated the same way (though tops out at a critical range of 5-20).

Hit Locations

When a critical hit is rolled or a target is reduced to zero hit points, [3] roll on the Hit Location table (use a lame 1d6 or use these super-bitchin' dice):

1d6  LOC.      MIN. DMG (1)    NORMAL DMG (2) MAX. DMG (3)
1    Lf Arm    Armour (4)      STR -1         Lost limb (5)
2    Rt Arm    Weapon (6)      DEX -1         Lost limb (5)
3    Lf Leg    Knockback 10'   -1 to Move     Lost limb (5)
4    Rt Leg    -1 to AC        -20# to Carry  Lost limb (5)
5    Torso     Knock down (7)  Stunned (8)    Shot to the Heart (9)
6    Head (10) Stunned (8)     Knocked out    Head shot (11)
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1.  Use if the damage roll is a natural "1." Penalties last until
    treated (i.e., 2-7 hp worth of healing).
2.  Use if the damage roll is between "1" and the maximum die
    value. Save or effects are permanent. 
3.  Use if the damage roll is the maximum die value.
4.  Reduce armour (or shield) protection by -1 (destroyed if
    reduced to zero).
5.  Save to convert into a bleeder (death from blood loss in 1
    turn/level unless given 4-14 hp worth of healing); if save
    fails, limb is gone, but no further damage.
6.  Reduce weapon's damage die by one step (e.g., 1d6 becomes 1d4);
    weapon broken less than 1d4 damage.
7.  Requires a full action to get back on your feet.
8.  Stunned combatants are -1 to all rolls, AC, and Move.
9.  Death in 1 round per level or HD unless given 4-14 hp worth
    of healing.
10. If wearing a helmet, save to treat as next lowest crit
    category.
11. Decapitation, throat slit, or weapon embedded in skull type of 
    thing. Unless the victim was caught by surprise or somehow
    unable to act, he gets one immediate retaliatory strike at
    -4 before falling in a crumpled heap.
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Option: Instead of modifying the to-hit or damage rolls, reflect weapon proficiency by modifying the hit location roll. More on this later, but you're now on notice that it's coming.

Using this table, you'll quickly discover that it's hard to kill things, though combatants do get messed up. As a result, reserve this table for PCs, Big Bads, and "Boss" NPCs. For fodder, henchmen, and minions, just consider them gone when they reach zero hit points.

Soooo... the table. Too much? I like the idea of different results based the amount of damage rolled, but I think the entries can stand some improvement. That said, feel free to suggest said improvements in the comments section.

UPDATE (2/25/12): Edits resulting from playtesting: now all Max Damage crits are potentially life-threatening. Other results got shifted to the left, and I incorporated saves to make things more heinous interesting.

Next Up, Unfocused thoughts on religion, Evan-style
Listening To: Tears for Fears, Sowing the Seeds of Love
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1. Based on the optional damage location system for Chimera RPG: http://www.welshpiper.com/hit-locations/; the zero hit point limit was inspired by Robert Fisher (http://web.fisher.cx/robert/infogami/Classic_D&D_injury_table).
2. Traps, spells, falling, and other sources of damage won't inflict a critical hit, but they can reduce a target to zero hit points, so the system applies to anything that inflicts damage. This also allows you to deduct hit points for intangibles such as fatigue, disease,substance abuse, prolonged exposure to the elements, and going off on adventures without twinkies and beef jerky.
3. A character at zero hit points is still active and able to fight. However, he does so at whatever penalty is imposed by the Hit Location table, and if he's hit again, he has to make another Hit Location roll.