GURPS House Rules: Hit Location Penalties

What?
I've changed the hit location penalties to be in line with the size modifiers of the locations.

Why?
That the hit locations receive arbitrary penalties rather than penalties consistent with other creatures causes problems. The RAW penalties also make some locations, such as the skull, too hard to hit, and other locations, like the vitals, too easy to hit. This creates unrealistic incentives, such as reducing the desire for low-tech characters to wear helmets.

Imagine a robot that's the size of a human skull that floats around and shoots lasers from its eyes. You're at a -5 penalty to shoot this SM-5 robot with your own laser gun. In contrast, you're at a -7 penalty to shoot a human skull. This makes no sense.

The reasoning for the higher penalty to hit a human skull than a floating robot is that the human skull can move around. This falls flat for a few reasons. One, this should also apply to creatures like the floating robot; if it can move as quickly as the human skull, then it should be at an additional penalty to hit. Two, this doesn't seem consistent with the rest of the system--other things that move fast aren't at a penalty to hit. And three, the penalty doesn't disappear when the head is motionless.

I think there are two ways to represent the quick movement of the skull in the rules that aren't an arbitrary penalty to hit the skull. Either certain parts of the body can receive a dodge bonus to represent the ease with which they can move out of the way of attacks, or you can employ some form of evasive action which will give a penalty to target the location only when it's moving. More on that some other time.

For the purpose of these rules, I've decided to give the more mobile locations a +1 dodge bonus. I don't know if this is realistic, but it seems like a reasonable compromise that allows for consistency between the human skull and the floating robot.


Going by only the size modifiers, we get the following for a SM 0 human:

Head, SM -4, eight inches, spherical, -4 penalty (roll 1d6; 1-3 is a skull hit, 4-6 is a face hit; Mobile, +1 to Dodge)
Skull, SM -5, five inches, spherical, -5 penalty (Mobile, +1 to Dodge)
Eye, SM -9, one inch, spherical, -9 penalty (Mobile, +1 to Dodge)
Face, SM -5, eight inches, elongated box, -5 penalty (Mobile, +1 to Dodge)
Neck, SM -7, three inches, elongated box, -7 penalty (Mobile, +1 to Dodge)
Arms, SM -3, two feet, -3 penalty
Hand, SM -6, ten inches, -6 penalty (Fist is an additional -2 SM and +2 for spherical shape, giving the same -6 penalty; Mobile, +1 to Dodge)
Torso, SM -1, two feet, elongated box, -1 hit penalty. (Fat increases to +0 penalty)
Vitals, SM -6, eight inches, -6 penalty
Groin, SM -6, eight inches, -6 penalty (Includes reproductive organs and bladder)
Legs, SM -3, two feet, -3 penalty
Feet, SM -5, twelve inches, -5 penalty