Thin Skull

:see also No Skull
GURPS Power-Ups 6 pg 25
If using the Damage to Armor rules "gives the wearer half its original DR (round down)" from 1/3 HP would basically result in having no DR at all.
As an alternative: a GM might opt to avoid rounding and allow 0.5 DR to remain in such a situation, which seems more fair. It would still remove a Targeting Chinks in Armor penalty!
==pricing problem==
Normal skull is defined on pg 25 as:
*DR 2 (Partial, Skull, -70%; Tough Skin, -40%) [2]
The problem here is that this should in theory be worth fewer than 2 points (it's not -80%, it's -110%) but still "costs" 2 because of the -80% cap.
The following logic is flawed based on that: 
:An implicit DR 1 (Partial, Skull, -70%; Tough Skin, -40%) [1] would be a relative -1-point disadvantage.
The problem there is that you're not actually losing a full point's worth of advantage, since it was actually limited beyond that.
For this to be a fair discount, it needs to be priced out to exactly -80%. A couple ways to do this:
==Approach 1==
*allow a custom "Non-Flexible Tough Skin -20%" modifier, which would reduce the total to -90%. This makes sense because of the suggestion of Hurting Yourself applying to skulls.
*using the rules from GURPS Martial Arts (that Hurting Yourself applies even though it's just DR 2 instead of DR 3) could be considered a +10% enhancement. Something like "Extra DR +50%" but as a Limited Enhancement like "only for enemies hurting themselves, -80%".
==Approach 2==
*give the skull Hardened 1 +20%. Consider B284 that a Leather Helm or Leather Gloves also give 2 DR... bone is harder than leather! This brings the total to -90%
*despite what B47 says, consider Partial (Skull) to be worth only -60%. An average -6 to hit is a fair compromise since GURPS Martial Arts changed the skull to be only -5 to hit from the rear. This saves another 10% and brings the total to -80%.
**Given that Z69 rates the skull as equivalent to an "Occasional" Bane, -60% is appropriate per B46
==Approach 3==
*adjust -70 to -60 per 2
*adjust -40 to -20 per 1
*ignore the Striking Bone notes in MA, if people want hard skulls that hurt people they can just buy an extra point of skull DR
**same with shins, DR 0 shouldn't hurt anybody, buy DR for your shins
==How to make cheap skull DR==
If we consider additional points to be -20% NFTS -60% Partial, there's no way to save points by taking things like Ablative. Even though Ablative would be one way to get cheap rigid DR.
One way to do that might be to come up with a custom like "provides Extra DR +80%" to counteract the cost.
The end result being that it works out to a 0-point feature: you buy 80% more ablative DR.
This is balanced because it's actually much less cost-effective than ablative DR usually is, providing LESS THAN DOUBLE even though you can usually buy 5x as much.
==see also==
Skull has only 2 total DR was defined as a 0-point feature before this came out.
Category:Quirks