Let's take a baseline human: ST, DX, IQ, and HT are all 10s, making his Speed and Move both 5. If the character starts out at SM +10, he would be 64 yards tall (196 ft) -- body proportions would suggest his shoe is some 10 yards long (1/7 his height) and, according to the rules, he would Move 5 yards per Turn; half the length of his shoe!

Another baseline human, this time SM -10. He is 2¼" tall. If he buys up his Move by just one yard, he would Move at 6 yards per Turn, easily outpacing the giant who is more than 1,000 times his height and stride.

I find this sort of thing silly.  But I have a solution... of sorts.

Two, new stats: DU and WU.  Distance Units and Weight Units, respectively, would be needed in maybe one campaign in a hundred but, where needed, desperately necessary.  DU follows SM, so that a character whose size is doubled also has their DU doubled as well.  I have run multiple campaigns where people have been turned into GI Joes, only to learn that, at SM -7, their DU of .083 (1/12) meant they measured their running speed in inches not feet.  DU also applies to range for muscle-powered ranged attacks.  The elf is SM -1?  His sized-down bow is DU .66; so it's not shooting as far -- DU also increases the range mods: a target which is 20 yards away for everyone else (-6) is now 40 DU away for this character (-8).  This is also applied to jumping, swimming, climbing, flying, tunneling, and falling!

More on WU later.

Are you looking at 3E or 4E? In 4E, SM -1 comes with Move-1, and +1 SM comes wish +1 Move as well. So your SM+10 giant would have Move 15. I'm not sure how the G.I. Joe character would translate. A Move -5 - would that be 1/5 Move?

"Baseline human" doesn't compute with those radical Size Modifiers.

In 4e, SM is largely, mostly, 'zeroed' to changes in Size Modifier (IE it's nether and Advantage nor a Disadvantage), so if you want to change something that isn't currently affect by SM, you really should be spending the points.*

I'd check the GURPS Wiki (https://gurps.fandom.com/wiki/Size_Modifier) and see how much 'work' SM is already doing and decide if it really needs to be doing more.

Also realize anything you do to mess with SM will have spillover tot he SSR (Size, Speed, and Range table).


* Personal aside, I hate all the ways SM has been expanded already, so I'm pretty resistant to any more increases to it's reach (zing!), and I've always been of the opinion that SM needs to have points applied to it, as it's clearly acting as an Advantage/Disadvantage...

Read through this again, be wary with that last one.  Falling damage should be decreased for especially tiny creatures, so you may want to look into the Slam rules and figure out a relationship between SM and falling damage, and then not increase the distance (as that hasn't actually increased).

Also, they aren't shooting any farther, despite their tiny size... I get what you're trying to do, and it may be more "elegant" than simply scaling up and down ST and HP in relation to SM, but it's far less intuitive, especially when you're only discussing half the relationships.  Does having a smaller DU/WU decrease damage done?  And are you accounting for the fact that size and weight and strength don't scale linearly?

Actually, they are.  Granted: this was originally designed for muscle-powered weapons. After all, imagine a Liliputian trying to shoot Gulliver in the eye. If Gulliver's standing, the little guy would be lucky if the arrow reached Gulliver's chest. We're talking about propelling an arrow straight up the equivalent of fifty yards!

But, now you mention it, how many micrograms of gunpowder go into a cartridge when the gun is less than a sixteenth of an inch?  That thing is really going to shoot as far as a full-size gun?

And falling?  At SM -10, a person would reach maximum velocity in less than a yard... there is no difference for them between falling one yard or falling five yards. At the same time, you're suggesting that a Brobdingnagian (at SM 10) wouldn't be able to shoot an arrow at his own foot (50 yards below) without taking a severe penalty to hit?

I mean, we're talking basic physics, here. The 20" tall catapult on your desk is not going to be able to throw a stone the same distance as the 20' tall catapult out in the yard.  And the little one will do little more than annoy you while the big one kills you and the two guys standing behind you.

That's not what I was mentioning, but sure.


And take almost no damage.  Which is as it should be because less massive objects have a lower terminal velocity and less inertia.  That's what I'm cautioning.  The system is designed around SM 0 with the entire SM system a bit of a fudge to work with other SMs in relation to SM 0.

If you're scaling the entire group to a different SM, then your method is fine, you're just rescaling everything to make them the new SM 0.  However if you're trying to rework the entire SM scale so you can have Giants and Pixies and Joe Normal human int he same group, it going to get messy.

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And I'm pointing out that there is a game you are trying to warp around your physics.

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Which is already covered by the ST attribute of those catapults.

I'll repeat my last question above that you ignored:  "[A]re you accounting for the fact that size and weight and strength don't scale linearly?"

Yes, you're right. They don't scale linearly, it's more of a cube-curve (or however that's phrased). And, you're right, it quickly becomes very messy, which is why when I first thought of this, I put it on a back burner. And then computers improved to the point of doing the math for us and I thought, "Maybe now's the time to try again..."

I'm open to suggestions but I still think there's a problem here.

The fact is: the system is already making allowance for the cubed differential: 50% increase in height means the weight is tripled because x1.5³ is x3.375. Roughly tripled.

My problem is (a) the Move is not adjusted for the longer/shorter legs, the Reach is not adjusted for the longer/shorter arms, and (b) the Basic Lift takes no accounting of body size or muscle mass, so a person of basic ST would be paralyzed at greater size while someone the size of an ant would be a thousand times stronger than any little ant.

It's like the idea of King Kong fighting Godzilla. King Kong was usually depicted as some five stories tall, so roughly 50'.  Godzilla was taller than most buildings, usually about 300'!  Kong would barely come up to Godzilla's knee. The lizard would snatch up the little primate, bathe him in fire, and swallow him while attacking the city.

The original rules used to charge for different SMs. Then the designers said the advantages and drawbacks of different sizes balanced out... Except they forgot to apply them!  Currently, the only intrinsic benefit of greater size is changing lightbulbs and reaching the top shelf. Everyone wants to be tiny because you're harder to hit but just as strong and just as mobile as someone a thousand times your size (SM -10 to SM 10).  And, sure, you can buy up the big guy's ST and Move but you shouldn't have to!  The SM -10 guy actually gets points back for having Move and ST commensurate with his size (and, by the way, how does one lower their BL to less than 3 ounces, which is ST 1?).

My suggestion is that Reach and Move and Range all be adjusted on the same scale as height; and that ST and BL be adjusted on the same scale as weight. I would also recommend some kind of SM-based modifier for damage.  I'm currently using the following formula:

When attacking a smaller target, add the SM-difference to each die.  When attacking a larger target, add the SM-difference to the defender's DR.

SM 3 attacks SM 1, the damage gets an extra +2 per die.

SM -6 attacks SM -2, the defender gets an extra 4 DR.

This is why it's so easy to squash little bugs and so hard to hurt Godzilla.

I'm sure this will raise lots of criticism (and I do appreciate hearing from you) but anyone think I might be right, here?

maybe you should focus more on the game play. worrying over these kinds of details because you want, what, ultimate reality?, is just going to ruin your game. it would seem all of this would simply fight against suspension of disbelief in your game.

A lot of GURPS players actually find their suspenders of disbelief snapping over areas where the rules do not 'accurately model reality enough' for them.  So if Yestow's rules model reality "more accurately" for his group, and they enjoy them, good on them.


(Though I think Yestow is mostly aiming at discussion here, which is honestly not the best place to drum up rules discussion for a rather niche rpg system.)




GURPS already does this (in part) by scaling up and down the weapon, not the being wielding it (and in part by scaling the "Minimum/Maximum ST" of the being based on SM)

Have you looked in GURPS Biotech and Low-Tech?  That's where some of these SM scaling rules lay.

That's better handled through HP and damage via ST.  The smaller creature is doing less damage and has less HP (and might possible have a DR penetration penalty), the larger one does more damage and has more HP.  Possibly also DR, although, again, and I can't stress this enough, GURPS already accounts for this in creature/character design.

It's why elephants have ST 45, 45 HP, and DR 4*, and rats have ST 1.

I get you want an easy "how to rescale on the fly", but then it should be modeled that way, "These are the new minimum/maximums of stats and abilities based on SM that a Character needs" not "theses are the free benes/penalties a Character gets for changing SM".

GURPS is 'balanced' around SM 0, Joe Normie, humans.  You really can't 'easily' rebalance away from that without changing the entire balance point, which is why I said (to expound upon) "if all the PCs are shrinking, being 2 inches tall is now SM 0, refactor everything else".  And there are rules for this.

Are they simple and elegant?  No, but then SM is messy and somewhat kludgey to start with... I don't really think you can streamline it and make it elegant, but I'll be happy to watch you try and point out issues as I see them.



If you haven't checked out the rescaling and SM change rules in Low-Tech and Bio-Tech, I recommend it (it may help to resolve some issues or spark further refinement) and also (I just remembered it existed) check out GURPS GULLIVER by t-bone, it's pretty widely acclaimed as answering a lot of SM scaling issues and has 'quick rescaling rules' that you might find adequate.

https://www.gamesdiner.com/gulliver/

I don't use them, but then I don't tend to have rescaling issues (I don't have radically different sized PCs) and I tend to hew closely to "you have what you paid for"* as a GURPS standard.  But his GLAIVE rules are pretty neat and I keep wanting to use them, just never have a group that agrees...


*  Which is why I already have issues with the free penalties and bonuses SM tends to hand out.

this all seems like a circular logic argument. did you forget what point you were trying to make or are you just numbers obsessed. at what point in all of this did you factor in the fact that it is a role playing game and that in no way can it accurately become a real simulation of anything nearing real life.

Stuff like this makes me grateful I play 1e AD&D.

Oh, yes, because no one ever gets into rules arguments about AD&D.

This message was deleted by the user at 12:02, Wed 06 Apr 2022.

Oh yeah, that never happens with D&D.  1st ed he says?  Mmmm, I remember those weapon speed arguments...

And on that note, I believe it's time to put this to bed.