The material here is 'homebrew', it is non-canon.

This is a collection of houserules.

Feel free to add your own.

Height & WeightEdit

The 4th Edition GURPS rules relate a character’s height to their strength and their weight is unrelated to it. Nor does being overweight or fat affect your physical abilities. Frankly, in a game that I value for its excellence at reflecting the real world, I find these rules to be a major flaw.

Take a few well-known examples from popular TV programmes. Do you imagine that Sheldon Cooper from The Big Bang Theory at 6’1” is stronger than Agent Cho of The Mentalist at 5’10”? Can you picture Roseanne being a superb acrobat, able to swing one-handed from a chandelier, grab a McGuffin in passing, then release and do a flying forward roll out of the window?

I have worked out the following table of weight by height and strength:

Build Table: Core Weight in Pounds by Height & Strength










































































































By ‘core weight’ I mean the weight of a normal proportion of muscle, bone, and fat for someone of your height and ST. You will be about the weight given, but you can choose to vary it by about 10% either way because of variations in your physique – lean but strong, stocky without being fat, etc. Even though it includes fat (about 20% of body weight, a healthy level), this weight doesn’t count as ‘overweight’/’fat’ etc. for encumbrance purposes.

The figures are derived from Body Mass Index: an ‘average’ person of ST 9-11 will have a ‘medium’ BMI. ST 6-8 will be pretty skinny – 20% lower weight than average, 12-13 is 20% heavier, and the top strength allowable in my campaigns (50% above racial average) is 50% heavier.


The 4th Edition rule about excess weight not affecting physical performance is a poor choice, in my view. It runs so contrary to what we all know of the real world that it jars. I cannot imagine fat people performing physical actions at the same level of ability as an ideally-built person with the same level of fitness. I liked the GURPS 3rd Edition system of excess weight being treated as Encumbrance, but decided that to make the impact of being overweight consistent with the cost of its effect on a character’s Dodge score, it needs to be tweaked somewhat. The cost of each level of overweight includes points for the social and practical disadvantages (restricted choice of clothing, people don’t find fat people attractive in most of the settings we play in, and the various other restrictions listed in the Characters book), and an additional amount to compensate for the effect on Dodge.

Overweight people have enough excess weight to take them halfway to Lightly Encumbered (round up) even when carrying nothing but normal clothes. -15 points

Fat people’s excess weight takes them to the minimum for Lightly Encumbered (that’s -1 to Speed, Move, and Dodge). -25 points

Very Fat people are so heavy that they start at Medium Encumbrance (-2 to SM&D). -50 points

Thus a ST10 Overweight person will have 10lb encumbrance of fat, a Fat person 20lb, and a Very Fat person 40lb. The equivalent for ST14 will be 20lb, 78lb, and 117lb. (NPCs may go up to Morbidly Obese: Heavy Encumbrance.)

If a player wants their character to be Very Fat but not suffer for it in combat, they can of course spend 40 of those points to buy +2 Speed, which will cancel out the effect of that encumbrance on their Dodge (and initiative, for those who use the standard initiative system – I use my Initiative house-rule). Or they could spend the 40 points to increase their Move. This reflects those few people who are fat, but fit enough to match slimmer people in some aspects of physical performance.

GMs whose campaigns feature Fatigue Points regularly may want to increase those point values. My campaigns hardly ever feature ‘endurance’ scenarios where the characters cannot sit down and rest at regular intervals during or after exertion, so we rarely bother monitoring Fatigue Points except when casting magic. But if for example you are running a Zulu campaign where the characters are expected to run for four days and fight a battle at the end of it, you may want to increase the value of the disadvantage. Characters with 78lb of excess fat wobbling around their bodies will probably need to buy Very Fit just to keep up with those whose only encumbrances are a loincloth, shield, knobkerrie, and assegai.

Will Points (WP)Edit

Why Will Points?

In reality when you make a bad decision, you make that bad decision. Putting it up to chance (will rolls) takes away that decision, it makes it not be a decision. Disadvantages encourage role-playing, but self-control rolls don't reflect the real-world. Will Points give the characters a pool of points they can expend to make good decisions when they want to make bad ones, or when it's easier to make a bad decision. They are intended as an optional rule for use in campaigns in which Will and Self-Control rolls are common, such as GURPS Horror™ campaigns.

+5 points per +1 WP

A new Secondary Attribute, Will Points (WP), based on IQ. Will Points represent your self possession and mental energy. Will Points can be expended on a failed Will or Self-Control roll to turn failure into success, this costs 1 Will Point.

Effect of Lost Will Points Edit

Sudden loss:Edit

1/3 WP
You are losing control of yourself, doing anything but lying around requires great mental effort.
0 WP
You completely lose control, if you're ever tempted to do something you do it, no thinking no nothing, just do it. Do it now. You automatically fail all Will and Self Control rolls.
At this point you are suffering a mental collapse, all your disadvantages effect you all the time and are more extreme. Any quirks you may have become as powerful as disadvantages (congenial becomes Chummy, Nosy becomes Curious, etc). In addition every hour roll 1d on the table below (symptoms replace each other):
random violence

Gradual decline:

0 WP
You are losing control of yourself, doing anything but lying around requires great mental effort.
You can no longer control yourself, if you're ever tempted to do something you do it, no thinking no nothing, just do it. Do it now.

You could combine these options in any way, but the recommended combinations are Expensive/Fast/Gradual and Cheap/Slow/Steep.


Recovering Will Points Edit

Mental rest is not the same as physical rest. Mental stress is increased at any time you stop yourself from doing something you want to do, whether that's yelling at someone or smoking a cigar. Recovering will points requires spending time in a non-stressful environment.

Optional Rule:Determine Success & Failure

You fail automatically on any Will or Self Control roll, the only time you succeed is when you decide to expend Will Points.

To determine the number of points this costs with the Expensive option, assume you had rolled a 10 and see how much you would've succeeded or failed by, if it would've been a success this costs only 1 point, otherwise the cost is equal to what your margin of failure would've been.

Recovering Will Points usually means a vacation or a stay at a mental facility. Roll Will once per day of mental rest, on a success you recover 1 Will Point.
Therapy expedites recovery, see page 425 of GURPS Campaigns™, except the appropriate skill is Psychology not Physician. Note that there is no equivalent for First Aid, Bandaging, Treating Shock, or Surgery; though the GM may extend this with optional rules for equivalents of those, using the Pharmacy skill for example.

Alterations These rules are untested and there are a lot of ways to change them. You might base WP on Will instead of IQ, make the cost equal to your margin of failure, have WP recover as fast as Fatigue Points, make the effects of lost WP more gradual, or probably a million other things.

Threads from the GURPS ForumsEdit

Several people discussed Will/Sanity points on the forums,

Everyday Spell Edit

In some fiction, you have spellcasters of sufficiently high power or skill casually using magic for everyday whims; for example, warming or stirring a cup of coffee. GURPS standard rules optionally allow this if the spell is known at a skill level of 15+ (GURPS Magic p.8-9). This has two unforeseen (and usually unwanted) effects: allowing IQ 14 Magery 3 casters to do this using spells with which you haven't gone into great depth, and rendering this ability out of range of your typical IQ 12 Magery 1 hedge wizards. However, if you link the Fatigue and Ritual reduction to Effective Skill rather than Base Skill, these Hedge wizards can pull it off with a Task Difficulty Modifier for "non-stressful everyday usage" (+4). Furthermore, Wizards who attempt really tricky uses of their spells will have to put more effort into them.


Initiative rolls (in the sense of when characters act in the turn sequence) are 2d+DX. That way, the more dextrous combatant (grabber, escaper, whatever) will usually be the fastest, but can't count on it. Unless she's up against a 4-DX zombie and has more than 12 DX, in which case the poor zombie had better get used to disappointment.They also change every round. It stops characters with high Basic Speed from becoming complacent about always getting in first.

Modifiers obviously apply in appropriate circumstances: if your 13-DX fighter is advancing with broadsword in hand on a 4-DX zombie with a Reach 2 spear, the zombie is still definitely going to have the first attack!

Carousing and Sex AppealEdit

Carousing and Sex Appeal are both based on HT in the standard rules. I can't see the justification. There are some social environments where your popularity may be based on your ability to out-drink everyone else (high HT is good!), but there aren't many. And why should anyone's success with the opposite sex be related to the number of days they've had off sick?

Instead, I base both on Perception. If you go into a bar, your ability to fit in with the patrons and talk them into having a good time (in the sense of both skills!) is related to how well you can read their mood and the way that your approaches are being received. It's very easy to cross the line between the life and soul of the party, and an obnoxious boor that everyone wants to avoid. In relationships, you need to be able to judge the moment when it is appropriate to move from friendly getting-to-know you chat, to intimate, shall-we-take-this-elsewhere seduction.


I have never been happy with the official GURPS language systems. I have therefore produced a house rule to introduce different levels of difficulty to learning languages. See the Languages House Rule page for details.

New DisadvantagesEdit

Macho (-10 points)

You will not resist a challenge, no matter how stupid you have to be, to keep up your image. Someone clucking like a chicken is all it takes to get you into a suicidally risky situation. You might kill or torture someone, even though you know it’s wrong, against the law, or might mess things up later, just to make sure no-one thinks you make empty threats.

You won’t do things that your particular social group (the one that you come from, not the rest of the PCs!) perceive to be ‘sissy’ or ‘conformist’ – in some societies that might include ballroom dancing or having a haircut. You will do stuff that may be against the law/rules of ‘normal’ society because it’s the ‘rebel’ thing to do: carry a concealed gun, or refuse to cover your gang tattoos or wear ‘normal’ clothing.

There is an up-side to this disadvantage, though: you have a +2 bonus to resist Intimidation.

Trigger-happy (-10 points in high-tech campaigns, -5 where firearms are not commonly used)

Whenever surprised, you will react with the maximum aggression at your disposal. Generally that means shooting or lashing out with a melee weapon at who- or whatever surprised you. This is an instinctive reaction, and happens regardless of how important it is to keep quiet to hide or achieve surprise, and you will not pause to identify the target exactly (i.e.: you will shoot your friends if they surprise you). For more information and an example, see the Trigger-Happy page.

Mental FragilityEdit

Every character has the Fearfulness trait, although it's at level zero by default.

Whenever you fail a Fright Check, but do not suffer any lasting effects from it, you gain points in Fearfulness equal to the margin of failure. Fearfulness costs -2 points per level, so you end up with a fright check penalty equal to half the margin of failure.

Fearfulness gained this way can be recovered. Every day, at the same time that you roll to recover HP, make a Will roll; you lose points in Fearfulness equal to the margin of success. Failures do nothing.

Since you can only make the recovery roll once per day, you will need to stay well out of harm's way in order to avoid pushing your fright check penalty to the point where you're all but guaranteed lasting mental disability. This makes it an appropriate stand-in for Call of Cthulhu's SAN loss.


Various house rules for GURPS Spaceships.