Well, now that the cat is most definitely not in the bag, here's what I did to d20 combat to make it more realistic, if you're interested. I tried to avoid the pitfall of making it more complicated. Overall, there is a roughly equal number of rolls compared to straight D&D. Let's start with the basic assumptions:
1) Combat should be as dangerous to equally-skilled combatants at low levels as it is at high levels. Two first level fighters will take maybe two to five rounds, or about ten to thirty seconds, for one of them to drop. I don't mind if high-level combatants take longer to kill eachother, but it shouldn't take ten times as long as it does in stock D&D.
2) Instant death should almost always be possible for any combatant.
3) Armor, dexterity, and shield use all contribute to your ability to survive an attack in different ways. The rules ought to reflect this to better simulate reality so that heavy-armor types are simulated accurately as compared with very nimble low-armor individuals. (Ace, you and I disagree about this).
4) Your skill with a weapon should allow you to deal more damaging attacks in addition to being able to hit your opponent more often. Likewise, most of standard D&D's circumstance or terrain-based modifiers to hitting the enemy should directly affect how much damage is inflicted.
5) Skill with a melee weapon will automatically make the wielder more adept at avoiding attacks, whether by evasion or deflection.
6) Weapons fit into broad groups that are fundamentally similar in use and design, so that one's training will be cross-applicable to many different weapons.
Now, the fixes:
Instead of BAB, armor class, and damage rolls, there are a few skills that are used in d20 combat instead. Basically, combat works by attack rolls and defense rolls. The attacking character rolls a d20 skill roll. The defender 'takes a 10' on a defensive skill roll and subtracts it from the attack roll. A damage number is multiplied by the result (called the Margin of Success in some games). Instead of hit points, a character has a defined value, Toughness, that will show how much damage is required for different severities of wounds. Action penalties are assigned according to the number and severity of a character's wounds. Enough aggregrate damage will kill the character.
Damage = (attack roll - defense roll) * damage multiplier
If the Damage from an attack is less than zero, the attacker missed or was parried. If it is zero, the attacker 'tagged' the defender but did not cause damage because the blow was too soft.
Your attack roll looks like this:
d20 + weapon skill + str or dex bonus depending on weapon (swords and axes, str; bows and finessed rapiers, dex).
Your opponent makes a defense roll:
d20 + defensive skill + dex + shield bonus (if any. This is here because shields help you block things most of the time instead of absorbing damage like armor).
The defensive skill may be either a melee weapon skill or a new skill, dodge. If you dodge, you may have to take a 5' step or else be hit anyway (details on that to follow if there's interest).
The damage multiplier is figured thusly:
Take the average of the die code, round down, and add the character's strength bonus and any other applicable bonuses. (Example: a fighter with a str 14 and a longsword. The sword's d8 becomes a 4. Adding in the str bonus of +2 results in 6).
The Toughness of a character is where the armor comes in. Toughness T is equal to some constant (I believe I chose 5, Don't have my notes in front of me) plus his constitution bonus, plus any bonuses he purchased through feats (the Toughness feat is the way that fighters gain Super Roll With the Punches ability in my version). For math geeks, like this:
5 + con + armor bonus + shield bonus + bonuses from feats
Now that we know how tough the character is and we know how bad the hit was (from the margin of success of the attack * the damage multiplier of the attacker), we need to know the severity of the resulting injury. Basically, different multiples of Toughness (T, 2T, 4T, 8T, etc) define how much damage causes a Minor Wound, a Major Wound, a Mortal Wound, or an Instant Kill.
I haven't tweaked all the threshholds for the different wound levels or the penalties for them, or exactly when death will occur from multiple minor or major wounds yet. But, what I do know is that a mortal wound is equivalent to being at zero hit points (that is, only partial actions and strenuous activity produces a likely fatal unconsciousness), an instant kill is unrecoverable death (short of resurrection or perhaps magical healing that round), and that minor wounds will likely have a -1 penalty.
What do you think? I know it is still in the rough draft phase. There's a lot of hidden subtlety to how I chose the different rules. For example, note that a bonus or penalty on the attack or defense roll hit automatically affects the severity of the damage inflicted. This will make D&D's various to-hit bonuses more valuable, which I think they ought to be.
More of d20's original rules are there than you might think, too. The maximum dexterity bonus as defined by a type of armor still applies, but it will reduce the dex bonus to the defense roll instead of the armor class. Also, 'dodgy' characters can dodge very well (as we all know, most low-armor types get a high armor class in default D&D anyway from a higher dex and masterwork/otherwise special armor), but they pay a penalty vs. 'blocky' characters who can melee very well because their dodge skill may require them to take a 5' step to avoid the blow unless they dodge very well (the specifics of this mechanic are still in revision).
That's my contribution. I'll repost this in its own thread once I've made more revisions, or in this thread if it lives long enough.
-S
