A damage system for LogST

[Infornific]

Originally Posted by dataweaver

No, and no. You're not thinking old enough: what I recall was from back in the late 90s/early 00s, well before the Fourth Edition had even been announced.

Were the forums even around then? It sounds more like something from gurpsnet. I remember ideas about log damage but nothing like that.

[Anthony]

Here's a pretty simplified one that should allow using most GURPS mechanics:

ST-powered weapons have a basic damage of 3d6+ST±n, where n depends on the weapon (and is generally going to be negative). Other weapons have a basic damage of 3d6±n. For non-ST weapons, n is equal to 20 * log10 (damage dice); a 1d weapon does 3d+0. Likewise, armor has a logDR, equal to 20 * log10(DR). Characters also have a Toughness, which is equal to ST-3, and Hit Points equal to HT (not ST).

If a character has only Toughness, subtract it from damage and apply the remainder to hit points. However, a non-crushing attack will always do at least 1 damage. If a character has DR, an attack whose damage is less than DR does no damage. Otherwise, use Combined Defenses to get a total Toughness.

Combined Defenses
Because this is a log system, defenses do not add directly. Instead, to determine the sum of two defenses, take the larger, and an add a bonus based on the difference between it and the smaller, as follows:

• Difference 0: +6
• Difference 1-2: +5
• Difference 3-4: +4
• Difference 5-7: +3
• Difference 8-10: +2
• Difference 11-20: +1

(note: these values are rounded slightly for ease of remembering).

Armor Divisors
Armor divisors reduce armor (but not toughness), as follows:

• /2: -6
• /3: -10
• /5: -14
• /10: -20

Apply this reduction before combined defenses.

[pierseb]

Originally Posted by Anthony

Combined Defenses
Because this is a log system, defenses do not add directly. Instead, to determine the sum of two defenses, take the larger, and an add a bonus based on the difference between it and the smaller, as follows:

• Difference 0: +6
• Difference 1-2: +5
• Difference 3-4: +4
• Difference 5-7: +3
• Difference 8-10: +2
• Difference 11-20: +1

(note: these values are rounded slightly for ease of remembering).

Armor Divisors
Armor divisors reduce armor (but not toughness), as follows:

• /2: -6
• /3: -10
• /5: -14
• /10: -20

Apply this reduction before combined defenses.

Are you using the same progression as «Knowing your
own Strength»?
If so, shouldn’t it be :

• Difference 0: +3
• /2: -3
  ...

With halving/doubling -3/+3
I’m probably missing something.

[dataweaver]

Know Your Own Strength uses a decibel scale for lifting (where +10 ST = ×10 lift), and regular GURPS tends to assume that damage scales with the square root of lifting (that is, damage increases linearly while lifting increases with the square). That would imply that it should take 20 levels of LogST for ×10 damage.

The catch is that in that article, damage doesn't scale with the square root of force; it scales linearly with ST while lifting scales geometrically. Adjusting the table in that article to operate off of the difference of ST vs. Body instead of just being based off of ST mostly implements my initial suggestion in this thread, but does violence to mathematical symmetry.

[dataweaver]

Reformulating my proposal with Knowing Your Own Strength as the baseline (instead of a vague “let's use some sort of LogST” statement):

No changes up through Logarithmic Basic Lift. Rescaled Damage is mostly the same, with the difference being that the damage dice are determined by (ST - Body + 10) instead of just ST. This removes the purpose behind the Rule of 10s and Fractional Damage, so ignore those sections: the damage that mice do to other mice works because of the ST-vs-Body relativity, not because small STs shift to a pseudo-exponential progression. Also, there's no floor for ST, not even zero. ST can and does go into the negatives for sufficiently small creatures; so does Body. This isn't a problem because of the shift to relative ST-vs-Body levels rather than absolutes.

Weight-based Hit Points becomes Weight-based Body, and that takes on a Logarithmic relationship similar to the new relationship between ST and Basic Lift. Given complaints about large things not having enough HP in 4e by such experts as David Pulver, and given the goal of making scaling easy to do, I would exactly mirror the relationship between ST and Basic Lift onto Body and Mass: if you're ten times as massive, you get +10 Body.

Pricing Revised ST gets some changes. Instead of HP, you buy and sell off Body at 2/level. The cost of Body is part of the cost of ST, so you're splitting 8/level between Lifting and Striking ST. Kromm is right about lowering the cost of Striking ST to 3/level, which leaves Lifting ST costing 5/level.

The rest of the article is unchanged.

[dataweaver]

Note that “Body is to Mass as ST is to Basic Lift” isn't all that realistic — but then, a realistic treatment of the relationship between ST, Body, Mass, and would be a heck of a lot more complicated than what we now have: you'd need something like TBone's old Natural Encumbrance system to reflect the fact that Mass tends to outpace Basic Lift as you get bigger, and that the consequences of this are rather troublesome, and potentially lethal (ask a beached whale about the problem of the square/cube law).