Critical Hit Effects in GURPS

What?
I've altered the effects of critical hits in GURPS to remove what I perceive to be the unrealistic aspects. I've tried to give results that can be explained as physically happening in the game world.

Why?
I think I need to begin by looking at what critical hits are and why we have them in the first place. As I understand them, their purpose is to give us a mechanical way of representing outcomes that are otherwise below the game mechanics' level of resolution.

Critical hits have two effects:
1) They remove the defender's chance to defend against the attack.
2) The attacker makes a roll on the critical hit table and gets a supposedly physically possible effect with a low rate of occurrence.

In regards to #1: I don't see how the critical hit rates would differ based on skill. I'm not familiar with earlier editions of the game, but I imagine this was acting as a pseudo-deceptive attack before that rule existed. That skill is tied in with #2 seems extremely odd to me, though. I can't justify highly skilled characters experiencing those essentially random and uncontrollable outcomes more often. It seems strange that a critical hit, something external to the defender, removes the defense roll entirely. It's difficult to explain how a robot with reflexes a thousand times faster than a human's can fail to defend against one attack in eleven from a human swordsman, regardless of the swordsman's skill.

Now my major concern: The critical hit table in GURPS gives results that don't make any physical sense. What does damage in GURPS represent? Kinetic energy. It's what determines whether an arrow pierces a bronze cuirass and it's what determines whether a bullet pierces a tank's glacis. What, then, do the double and triple damage results on the critical hit table represent? Clearly they are an increase in kinetic energy. I find this incompatible with reality. Ten damage is 625J, nearing the upper limit of human muscles. Thirty damage is 5625J, which is well beyond anything the human body is capable of. A bow or gun, or a human's sword arm, don't function this way. I can't conceive of this result ever happening in an unpredictable manner. If my gun occasionally shoots for triple damage, then clearly I should be able to alter its mechanism so it always shoots for that amount of damage. If you look at Olympic athletes and the results they get at events, their muscle output is consistent, with variations of one or two percent. If human muscles, guns, lasers, and all other weapons outputted five or ten times their normal wattage as GURPS claims they do, this would show up in measurements of athletes and firearms.

The ability to ignore some amount of DR also makes little sense. It can't be explained as a flaw in the armor in anything other than a narrativistic sense; what if my armor really has no flaws? Does the critical hit travel backwards through time and cause the smith to work weak spots into the armor? Weak spots that can't be detected by even the most advanced instruments (for the DR of homogenous TL12 robots and vehicles are also halved).

Why would a TL11 war robot drop whatever it's holding because it was struck by a man with a sword? Why would this continue to happen after that model's next firmware update?

I don't believe these results are intended to explain the physical goings-on of the game world itself. The results they provide can't be explained in terms of the physics of the in-game universe. When using these rules, I am unable to achieve the desired sense of verisimilitude.

As such, I offer these alternatives:

The rules:

Critical hits no longer remove the defender's chance to defend. I am considering three options here. Option #1: no defense penalty, defender defends as normal; Option #2: defender defends at -4; Option #3: defender defends at half of the attacker's margin of success on his attack roll.

I think I prefer #2 here for ease of use, but I could argue for either of the other two.


And here is my new critical hit table:

3 You may change the hit location of your attack to any other of your choice.
4 Maximum Damage.
5 Your opponent can't retreat from this attack.
6 Shock penalty from attack lasts an additional 1d seconds.
7 Attack is at an additional -2 to defend against.
8 You get +3 on defenses against the attacked target until your next turn.
9, 10, 11 No additional effect.
12 Same as 8
13, 14 Same as 7
15 Same as 6
16 Same as 5
17 Same as 4
18 Same as 3

GURPS House Rules: Shields as Cover

What?

I've changed the way shields work so they're more in-line with the way armor works. Rather than granting a defense bonus, they provide DR against attacks that strike them.

Why?

Imagine this: you're a Greek soldier standing with your comrades facing off against a Persian army. You're in a field with grass up past your eyes. A cloud of dust so thick it blocks the noonday sun fills the sky. You have only your helmet, your shield, and your spear to protect you from the enemy. The arrows rain down upon you. You don't see them. You can barely see the men at your side. You raise your shield to protect you... and the GM speaks: "You don't see the arrows. No defense roll."

Your shield might as well not exist. It doesn't exist, as far as GURPS cares.

Another scenario: you're a Viking warrior. Much like the hoplite, you're armed only with your helmet, your shield, and your spear. You fight in much the same way as the Greek before you and the Sumerian before him: in a mass of men standing shoulder to shoulder with a shield in one hand and a spear in the other. Your foe is much the same, though unlike the Greek fighting the Persians, you fight your neighbors from across the river. There are no ranged weapons on either side, only spears and shields and the rare man on horseback. You march forward and press your spear toward your enemy, holding your shield close. Your brother is on your left, your uncle on your right. Not far off, you can see your father. As the mass of men collide, your brother takes a spear to the face. He falls to the ground. All thoughts of your own safety disappear and you enter a violent rage. You make your strongest thrusts at any opening, striking at maximum distance. Your shield is still there, though, between your chest and your enemy's spear. Your enemy stabs at your torso, and... again the GM speaks, "Yeah, he hits you in the torso. Four injury to your vitals."

In GURPS, any time you can't defend, or fail to defend, your shield is nowhere to be found. The space it occupies is considered empty by the game. Where there should be a large piece of wood and leather and metal, there is nothing. The enemy never accidentally strikes your shield. The enemy never takes deliberate action--at a penalty to hit--to get around your shield. Because it simply isn't there.


The rules:

Shields now provide DR as cover rather than a bonus to defend. Shield DB is no longer a thing. You may Block with your shield as normal, but it provides no bonus to your Block roll. It also provides no bonus when dodging or parrying. In this way, Blocking is in essence identical to parrying. Perhaps it would be best to abandon the notion of Blocking as a separate concept altogether and only have dodging and parrying, with shield parries being identical to parries with any other weapon.

Shields are treated as cover all the time. Whenever you have a shield near your body, it's providing cover against both melee and ranged attacks.

First: apply the "thin slab" rule for determining shields' cover DR. Ignoring this rule results in obvious nonsense cover DR values for shields. The Roman Scutum in Low-Tech has a Cover DR of 10. More than all but the thickest steel armors! There's no way that's right. So we'll be using its actual DR, without adding any of its HP, which gives us a DR of 4. Much better. This is a good place to note that these rules are intended to work with the realistic damage values of The Deadly Spring, and some theoretical similar treatment for melee weapons, slings, and so on.

Next, these work just like normal cover. It's a -2 penalty to bypass cover. This number may need to be revisited, but it works well enough for now. Note that massed missile fire never does this.

I've attempted to formalize what areas are protect by shields in different circumstances, but this will obviously need GM judgment to adjudicate at times. That's a feature rather than a bug. If you want to cover your shins with your shield, then the GM will have to determine how much your knee is protected. This is normal for cover! All the cover rules work this way. It's no different from if you kick over a table and stand behind it. I've given some examples, but these certainly aren't intended to be all-inclusive.

Also, for the sake of completeness, I've added protection chances for when you are presenting a single side of your body toward your opponent. We don't exactly have rules for this now, but these values will be useful later on when we do. I'll do another post on that some other time.

Otherwise, these work just like armor. You have a location and the shield provides DR for that location. Some of these provide only a chance. For instance, if a shield gives a 4/6 chance to protect an area, roll a six-sided die. On a one, two, three, or four, the shield protects. On a five or six, you receive no protection.

One more thing. The dueling buckler is a special case. It provides no cover, but gives DR 4 to the hand. It can block as normal.

All shields provide cover only against attacks from the shield side and the front. If other areas are protected, such as when on horseback, or when the shield is carried on the back, GM judgment will be necessary, as I have no formal rules for those situations as of yet.

The short version: shields give DR, just like armor. It's a -2 penalty on your attack to bypass the DR. This replaces all the other stuff shields did. You can still Block, but shields give no bonus to any of your defense rolls.


Here are my examples. These are meant to demonstrate the concept. I make no claims of their exact accuracy.

Hoplon or Scutum - DR 4
               Front/Weapon  Front/Complete
Skull               -           -
Face                -           -
Neck                -           -

Chest               - 3/6*      - 6/6
Abdomen             - 3/6*      - 6/6
Groin               - 6/6       - 6/6

Left Shoulder       - 6/6       - 6/6
Left Upper Arm      - 6/6       - 6/6
Left Elbow          - 6/6       - 6/6
Left Forearm        - 6/6       - 6/6
Left Hand           - 6/6       - 6/6
Right Shoulder      -           - 6/6
Right Upper Arm     -           - 6/6
Right Elbow         -           - 6/6
Right Forearm       -           - 6/6
Right Hand          -           - 6/6

Thigh               - 3/6*      - 6/6
Left Knee           -           -
Left Shin           -           -
Left Foot           -           -
Right Knee          -           -
Right Shin          -           -
Right Foot          -           -


*Increase to 5/6 if presenting shield side.



Kite Shield - DR 4  
               Front/Weapon  Front/Complete
Skull               -           -              
Face                -           -              
Neck                -           -              

Chest               - 3/6*      - 3/6*  
Abdomen             - 3/6*      - 3/6* 
Groin               - 3/6       - 3/6*

Left Shoulder       - 6/6       - 6/6          
Left Upper Arm      - 6/6       - 6/6          
Left Elbow          - 6/6       - 6/6          
Left Forearm        - 6/6       - 6/6          
Left Hand           - 6/6       - 6/6          
Right Shoulder      -           -          
Right Upper Arm     -           -          
Right Elbow         -           -          
Right Forearm       -           -           
Right Hand          -           -           

Thigh               - 3/6*      - 3/6*
Left Knee           - 3/6*      - 3/6*   
Left Shin           - 3/6*      - 3/6*  
Left Foot           -           -              
Right Knee          -           -              
Right Shin          -           -              
Right Foot          -           -

*Increase to 5/6 if presenting shield side.



Heater Shield - DR 4  
               Front/Weapon  Front/Complete
Skull               -           -              
Face                -           -              
Neck                -           -              

Chest               - 3/6*      - 5/6          
Abdomen             - 3/6*      - 5/6          
Groin               - 1/6**     - 1/6**        

Left Shoulder       - 6/6       - 6/6          
Left Upper Arm      - 6/6       - 6/6          
Left Elbow          - 6/6       - 6/6          
Left Forearm        - 6/6       - 6/6          
Left Hand           - 6/6       - 6/6          
Right Shoulder      -           - 6/6          
Right Upper Arm     -           - 6/6          
Right Elbow         -           - 6/6          
Right Forearm       -           - 6/6          
Right Hand          -           - 6/6          

Thigh               - 1/6**     - 6/6          
Left Knee           -           -              
Left Shin           -           -              
Left Foot           -           -              
Right Knee          -           -              
Right Shin          -           -              
Right Foot          -           -

*Increase to 5/6 if presenting shield side.
**Increase to 3/6 if presenting shield side.

GURPS House Rules: Size Modifier, Part 1

What?
I've broken down the price of the different components of a positive Size Modifier.

Why?
A positive size modifier acts as a large negative disadvantage. I've priced out its different components to see what it would cost if you priced those traits out individually. Thanks to Bruno on the forums for breaking down exactly what SM is.


Here's what I get for SM+1 or Gigantism for a normal human:

[Varies] Buy ST, Arm ST, Lifting ST, Striking ST at reduced cost
[5] +1 Move
[2] Immune to Constriction Attack (Relative SM +1 or more)
[1] Easier to intimidate, harder to be intimidated (Relative SM +1 or more)
[1] Easier to pin, harder to be pinned (Relative SM +1)
[1] Can squeeze torso (Relative SM +1)
[1] Increased reach (Only for unarmed attacks)
[1] Easier to hit when you grapple (Relative SM +1 or more)
[1] Can trample/overrun (Relative SM +2 or more)
[1] Longer poison delay

Negative

[-5] Easier to be hit
[-1] Easier to be noticed by Vision
[-1] Harder to be camouflaged
[-5] Eat more food overall
[-1] Require more space and life support
[-20] Larger equipment costs more and weighs more
[-1] Harder to fit under low hanging ceilings and doorways without crouching or crawling, or through narrower cracks/holes (or even doors) without an Escape roll.



That works out to a total of -20 points before applying the discount for high ST, which, realistically for a human-sized creature, will give back around four points or so. My preference is to abandon the rule that gives larger creatures a discount on ST. I don't see what purpose it could serve other than to mask the fact that high levels of ST are overpriced. I'll address that in another post. I also strongly dislike that as a method of balancing size modifiers because not all large creature have a high ST or HP. You can have ghostly creatures that are very large but have no mass at all, similarly with large nanoswarms, balloon-like creatures, jellyfish, and weird aliens and supers. If their 0-point size modifier is supposed to be balanced by cheaper ST, then creatures who aren't buying ST are getting a bum deal. Even with SM+1 creatures, the ST 10 giant is suffering much more from his size than the ST 20 giant. I don't like how the value of the trait varies like that based on which other traits you've purchased.


In Conclusion

I would turn Gigantism or SM+1 into a [-20] disadvantage, and remove any reduced cost for a high ST.

GURPS House Rules: Parrying Unarmed Attacks

What?
I've changed what happens when you parry an unarmed attack with a weapon.

Why?
In the RAW, when you parry an unarmed attack, you immediately get to make a free attack against the limb of the person who attacked you. Furthermore, the soon-to-be-limbless attacker doesn't receive a defense roll against this free attack. This is a problem, first, because it breaks the action economy of the game. If you have the time to make a full-strength attack any time you can parry, then why are you limited to doing so only when you can parry someone's unarmed attack? Second, that they have no chance to defend makes unarmed attackers unrealistically vulnerable. They can't pull their hand back when they see their opponent's sword coming for their hand?


The new rule:

Whenever you parry an unarmed attack, on your next turn you can choose to attack the body part you parried at no penalty, with an attack maneuver, using your maneuver for the turn. The body part's owner can defend as normal.


I believe this makes unarmed attackers, like martial artists or tigers, function much better as both player characters and enemies. No longer do unarmed monsters get eaten alive by men with swords.

Sample GURPS Supers character: Donatello

I thought it might be helpful to some people to see a familiar superhero made in GURPS. This is my very cinematic, crazy zany cartoonish version of Donatello from the Teenage Mutant Ninja Turtles.

Name: Donatello

Attributes [330]
ST 14 [40]
DX 16 [120]
IQ 16 [120]
HT 14 [40]

HP 14
Will 16
Per 12 [-20]
FP 14

Basic Lift 39
Damage 1d/2d

Basic Speed 8 [10]
Basic Move 8

Social Background
TL: 10
Cultural Familiarities: Western
Languages: English (Native/Native)

Advantages [381]
Ally (April; 25%; 12 or Less) [2]
Ally (Casey Jones; 50%; 6 or Less) [1]
Ally (Splinter; 100%; 15 or Less) [15]
Ally (Leonardo; 100%; 12 or Less) [10]
Ally (Michelangelo; 100%; 15 or Less) [15]
Ally (Raphael; 100%; 9 or Less) [5]
Ambidexterity [5]
Breath-Holding 5 [10]
Combat Reflexes [15]
Common Sense [10]
DR 1 (Tough Skin, -40%) [3]
DR 2 (Still Suffers Shock Penalties, -20%; Torso Only, -10%) [7]
DR 1 (Still Suffers Shock Penalties, -20%; Torso Only, -10%; Directional, Back only, -40%) [2]
Enhanced Parry 3 (Staff) [15]
Extra Attack 1 (Multi-Strike, +20%) [30]
Flexibility [5]
Gadgeteer [25]
High TL 2 [10]
Injury Tolerance (No Head; No Neck; Reflexive, +40%; Temporary Disadvantage, Blindness, -50%) [11]
Luck [15]
Metabolism Control 9 [45]
Perfect Balance [15]
Peripheral Vision [15]
Precognition (Meditating, -70%; Passive Only, -20%) [5]
Single-Minded [5]
Trained by a Master [30]
Unusual Background (Weird Science) [10]
Very Fit [15]
Wealth (Comfortable) [10]
Weapon Master (Staff) [20]

Disadvantages [-76]
Chummy [-5]
Code of Honor (Ninja) [-5]
Dependent (April; 25%; 6 or Less; Friend, x1) [-5]
Dependent Group (Family: Leo, Raph, Michelango, and Splinter; 100%; 6 or Less; Loved One, x2) [-1]
Disciplines of Faith (Ninja) [-5]
Enemy (Foot Clan; 9 or Less) [-30]
Secret (There's Mutant Turtles living in the sewers.) [-20]
Sense of Duty (Family) [-5]

Quirks [-3]
Hero When Able
Likes Pizza
Likes Rock and Roll Music

Skills [302]
Area Knowledge (New York City) (E) IQ [1]-16
Area Knowledge (New York City Sewer System) (E) IQ [1]-16
Blind Fighting (VH) Per+4 [24]-16
Breath Control (H) HT+2 [12]-16
Computers! (VH) IQ [24]-16
Connoisseur (Pizza) (E) IQ [1]-16
Disguise/TL8 (A) IQ-1 [1]-15
Encyclopedist! (VH) IQ-3 [3]-13
Fist! (VH) DX+2 [48]-18
Hidden Lore (Dimension X) (A) IQ-1 [1]-15
Hidden Lore (Mutagens) (A) IQ-1 [1]-15
Hidden Lore (Psionics) (A) IQ-1 [1]-15
Hidden Lore (Utroms) (A) IQ-1 [1]-15
Inventor! (VH) IQ+5 [84]-21
Move! (VH) DX [24]-16
Scholar! (VH) IQ-3 [3]-13
Science! (VH) IQ [24]-16
Thief! (VH) DX [24]-16
Throw! (VH) DX [24]-16

Equipment
Ninja Gear
Scavenged Science Equipment
Well-Furnished New York Sewer Apartment

Attributes [330] Advantages [381] Disadvantages [-96] Quirks [-3] Skills [302] = Total [914]

GURPS House Rules: Influence Skills Examined

Okay, so let's take a look at these influence skills and what I've done with them.

Here's the list we're starting with, from the rules as written:

Acting
Carousing
Diplomacy
Fast-Talk
Intimidation
Leadership
Panhandling
Politics
Public Speaking
Savoir-Faire†
Sex Appeal
Streetwise


And now what I've shortened this down to:

Deception
Diplomacy
Intimidation
Oratory
Savoir-Faire
Sex Appeal


What I've tried to do here is separate these into the means you're employing to influence the person. There was a lot of overlap on these before.

The means are:

Deceit. (Deception)
Appeal to mutual benefit. (Diplomacy)
Threats. (Intimidation)
Bamboozlement, eloquence, stirring of the emotions through powerful language, whatever you want to call it. (Oratory)
Appeal for in-group favoritism. (Savoir-Faire)
Sex appeal. (Sex Appeal)

Each of these skills employs a different means of achieving the desired end. This isn't the case with the RAW skills, which are often about the desired ends rather than the employed means.

Look at the Politics skill for example. It doesn't tell you what sort of means you're employing, only the ends you're acting toward. I think it makes more sense to have politicians engage in Diplomacy and Oratory--the means--than to give them a skill designed specifically for their ends. It's the same with skills like Leadership and Panhandling. Now, of course those uses will take familiarity penalties. Alexander won't be as good a panhandler as Diogenes, even if they both have the same skill levels, but I think that should be because Alexander is unfamiliar with the task and not because he's employing a different skill entirely.

I find the Acting and Fast-Talk skills particularly confusing. They both employ deception as their means, but you sometimes use one and you sometimes use the other. It's not at all clear what the difference is between the two, and I've seen this cause considerable confusion in the game. A character with a high skill level in one skill and a low level in the other will do something expecting to use their high skill level only to be told to use their lower one. These two skills are intended to be very dissimilar, judging by their lack of default, but they're nearly indistinguishable.

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