Gird Yer Loins! v1.2

Two Quick Ideas for Armor in GURPS

Copyright 2002, T. Bone, tbone@gamesdiner.com. All rights reserved. GURPS is a trademark of Steve Jackson Games, Inc. Copyrighted material appears courtesy of Steve Jackson Games.

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Update to 1.2 on 03/06/15. Added rules of thumb for setting armor DR and EP, and added to table of sample armor stats.

Update to 1.1 on 03/05/04. Beefed up the "drop PD" rules all around.

Minor update to 1.03 on 02/10/17 (Reduced multiplier in option for varying DR multiplier vs glancing blows based on PD stat; it was too high for armors like plate. Thanks, P. McCurry! )

Minor update to 1.02 on 02/09/29 (Frodo's armor was Dwarven, not Elven!)

Minor update to 1.01 on 02/02/27 (added notes on EP and Toughness)

Below are two quick, partially fleshed-out ideas for armor in GURPS. The first is a simplification: drop PD from the game! The second is a complication: an "Edge Protection" stat for armor, for more realistic simulation of armor properties.

Use either or both as you like.

Drop PD from the Game

Just dump it. What's it good for anyway? The first thing it does is cause trouble, raising the defense scores of well-armored fighters to that infamous GURPS "unbeatable defense" level.

GULLIVER suggests one possible fix: Split AD and PD, and make a check vs each separately. It avoids game-slowing high defenses and is a nice improvement, but I admit to often forgetting that PD check after a failed AD check. (Funny, players don't remind the GM when he forgets a monster's PD check...) And though it's a quick roll that's only needed if the AD roll fails, it's still an extra roll.

But what about PD's legitimate purpose, simulating deflection of a glancing blow? Well, DR alone deflects blows just fine if it's high enough. As for blows that DR normally wouldn't stop, PD aims to please, but it's not as simple as it looks. We don't want too powerful blows to glance off, so we have to adjust PD for these. Also, for some magical or other special attacks, we have to specify whether the attack ignores DR, PD, or both.

Although PD is supposed to simulate deflection of a glancing blow, it's funny that we don't first have anything with which to simulate the glancing blow itself.

Here's a new suggestion that does it all -- glancing blow and armor deflection -- in one simple, PD-less shot:

Active Defenses

Do not add PD to Active Defense. Say goodbye to PD.

Shields: One exception to the above: Do add a shield's current PD value (+1 to +4) to Block. This does not aid other defenses. It's a bonus that Block gains for the large size of the defending object, just as Parry takes a penalty when attempted with a small knife.

Glancing blows and deflection

A glancing blow is a graze, or any off-center, fleeting, or otherwise unimpressive touch that doesn't strike squarely.

Effects of a glancing blow: Halve damage, and multiply DR by some constant. Let's go with x2 for now.

(This approach -- effectively increased DR -- is the same one Vehicles applies to sloping armor. A glancing blow is simply one that strikes armor at a "slope".)

If an attack is connected with effects other than damage (such as a resisted spell), let a glancing blow offer +2 on appropriate resistance rolls.

Determining a glancing blow: A glancing blow happens if

1. The attack roll fails by 1 (it still hits, but weakly); or
2. The defense roll fails by 1 (damage is partially avoided).

These stack just fine, so a defense that almost succeeds against an attack that almost misses inflicts only 1/4 damage and multiplies DR by 4.

Playing it

We now have a realistic rule for glancing blows that will often reduce the damage dealt by a clumsy fighter or taken by a skillful defender. The blow hits armor at an angle, increasing the armor's ability to deflect the blow.

Without PD, we can also drop the GURPS complication of adjusting PD for damage dice. Just apply damage normally in a glancing blow; plain old DR picks up the role of PD nicely. A glancing sword blow will likely bounce off of plate mail's effectively doubled DR. A cannonball will plow on through just fine.

Further tweaks

Too-low Active Defenses: Some players may feel that without the addition of PD, Active Defenses become too low in GURPS. If that's the case with you, here are two suggested fixes:

1) Add a flat +2 to all Active Defenses, borrowing part of the rules described here. The minimum defense roll, for an Active Defense of 1, becomes 3, which is the minimum that can be rolled on 3d. Sensible!

2) Try defenses based on full skill levels, as described here. It's a more radical and untested approach, though.

Shields and passive protection: If you still want shields to offer passive protection, let them subtract their GURPS PD value from a foe's TH. After all, a shield is cover.

Use this full subtraction only for an attack from the defender's shield hex. Halve the TH penalty (round down) for other front hexes. There's no TH penalty for attacking a shield holder from the rear.

Comparison with GURPS shield rules: This article's shield rules are a real improvement over current GURPS, in which active use of a shield adds no more to your Block than passive use adds to your Dodge and Parry. The rules above sensibly award this bonus only to Block. With the added option of passive protection via a TH penalty, a shield can protect you a little no matter what you do -- but really aids you if you actually use it. Makes a lot of sense!

Varied deflection ability: You may object that under these rules, all armors of a given DR display the same ability to deflect glancing blows. This usually makes sense, and GURPS PD generally has a close relationship with DR. But yes, there is some variety in the PD that GURPS assigns to different armors of the same DR, which you may want to recapture.

Easy solution: Instead of multiplying DR by a constant (such as 2) after a glancing blow, multiply by (three-quarters GURPS PD for that armor, minimum x2). You now have varied deflection abilities among different armor types, based on the original GURPS PD stat.

Edge Protection

GURPS introduces a rule for flexible armors like Kevlar and mail: A bullet which does not penetrate these armors still inflicts one point of crushing "blunt trauma" damage for every 5 or 6 rolled.

Here's a different, more comprehensive way to handle flexible armor and blunt trauma from any sort of attack:

Edge Protection score

In addition to DR that negates the force of a blow, armor can offer lesser protection that allows the force of a blow through, but prevents an edge or point from penetrating the armor (and thus flesh).

This Edge Protection (EP) is measured in points like DR. Simply put, DR represents resistance to any deformity at all; EP represents resistance to penetration. Tough, flexible material has low DR, high EP. Tough, hard material has high DR, low EP.

Setting DR and EP: The more flexible the armor, the more that protection will take the form of EP instead of DR.

To rework existing GURPS armors, below are rules of thumb. However, any armor can vary considerably from that, especially in EP.

• Flexible armors like mail: Set EP to about DR x 1.5, then cut DR to a third or less.
• Semi-flexible armors like cloth and leather: Set EP to about DR, them lower DR by a quarter or so.
• Hard armors like plate: Set EP to about a third of DR, then lower DR by a quarter or less.
• Very hard armors like ceramic: Use DR as is with no EP, or turn about a tenth of DR into EP.

In the end, the armor's total DR+EP should be higher than the current GURPS DR (much higher, in the case of flexible armors), to maintain its overall level of protection.

Extreme cases: An Impenetrable Coat of Armor bequeathed by the gods might have no more DR than normal armor, but infinite EP. You can be bludgeoned to death wearing it -- fairly easily so if it's flexible with low DR -- but it won't be penetrated.

Make that a thin Shirt of Impenetrable Mono-silk, and you can have zero DR armor that's of no value in a fist fight, yet will stop a sword from running through you.

A theoretical very hard and strong but brittle armor, perhaps ceramic, would have high DR and no EP -- damage above DR simply breaks it.

Cost of natural EP: As natural armor, charge 1/3 the cost of DR to purchase EP.

Sample Armor Table

Below are standard GURPS armor types, reworked with new DR and EP stats. These loosely follow the rules of thumb given earlier, but not precise conversion numbers. Adjust freely to taste.

Sample armor table

Subtract DR normally from damage. These points are absorbed by armor. Damage beyond that, affecting EP, is crushing damage, even if the attack was cutting or impaling. These points deform the armor and bruise the flesh beneath, but do not penetrate the armor.

Edged damage beyond both DR and EP does penetrate the armor. (If you're using rules for accumulated damage to armor and deteriation, this is significant.) Treat as normal edged damage.

The rule replaces the GURPS "roll of 5 or 6" rule.

Example: You're wearing chain mail with cloth underneath, for DR 2, EP 5. An axe blow for 2 or less damage doesn't hurt you. A 4-point blow, after DR, leaves 2 points of crushing damage; the mail is not cut. (If that axe were poisoned, the venom doesn't touch you.)

A 13-point blow is reduced to 11 by DR. The next 5 points are crushing damage only, and don't cut the mail. The next 6 points break through the mail and cut you normally, for 9 damage after the cutting multiplier. You took 14 points of damage from the blow (5 crushing, 9 cutting).

A 2-point blow from a club does no damage after DR. A 4-point blow inflicts 2 points of crushing damage; a 13-point blow, 11 points of crushing damage. That's right, EP offers no special protection against crushing damage that exceeds DR.

Further tweaks

EP and attack types: Like DR, EP may vary with attack type. For example, halve both DR and EP for impaling weapons vs mail or Kevlar. Or your magic Impenetrable Coat's EP may drop to a low value (even zero) when faced with the magic All-Penetrating Sword.

Likewise, detail-oriented DMs will find EP a good way to model weapon sharpness. A blunt edge might double EP; a very sharp one, halve EP. (This further adds to the armor-piercing ability of fine weapons, without more damage adds.)

EP and bullets: As with edged attacks, EP represents armor's ability to turn a bullet into a crushing blow, without piercing the armor and entering the body.

Of course, GURPS considers bullet damage crushing anyway, so EP makes no difference in a normal torso shot! That's an unavoidable effect of GURPS' wacky decision that a bullet piercing the body has the same effect as a blunt crushing blow of the same basic hits. If bullets were properly gamed as impaling, then EP would make a real difference.

As it is, EP does make a difference when the vitals are a target (GURPS does treat them as impaling here), or when bullet caliber or make-up (such as hollow-point) would apply a damage multiplier.

Armor-piercing bullets should divide EP by at least as much as they divide DR.

EP and Toughness: There's no problem using EP with GURPS' Toughness, which, after all, is just DR.

How about GULLIVER's redefined Toughness? This is protection (generally from muscular or otherwise stout flesh) that lessens crushing blows a lot, slashes less so, or a stab to the vitals very little; it's in some ways the opposite of EP. (Game terms: Toughness only subtracts from the basic hits of a kinetic blow, not the additional damage from an edge.) Sounds like it's be hard to juggle DR, EP, and this new Toughness, no?

Turns out it's really very simple: Toughness and EP combine to form DR. A point of EP turns a point of edged damage into crushing, and a point of Toughness absorbs that point of crushing damage. (That's why suggested costs of Toughness and natural EP combine to the cost of DR.)

Example: You have Toughness 3, and put on DR 2, EP 4 armor. Toughness and EP combine to become DR 3 with EP 1 left over. Treat the total as DR 5, EP 1.

If you now wear DR 1, EP 1 armor, Toughness and EP combine to become DR 1 with Toughness 2 left over. Add this DR to the armor's DR: net DR 2, Toughness 2.

With EP to stop edges from penetrating, Toughness to model absorption of blunt force, and DR to combine the effects of both, you can easily model just about any armor effect. (And you don't even need PD!)

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