Revisiting ST (Strength) Rolls in GURPS

Edit: I do a lot of GURPS writing, but my audience is now broader than it used to be. That’s all to the good, of course. But: ST is Strength in GURPS. HT is Health. DX is Dexterity. HT and DX are 10 at the average, and relate to physical and mental robustness to physical effort and injury for HT, and the ability to control your body’s motions and objects – such as weapon attacks – for DX. ST is directly related to damage – each extra point of ST gives roughly an extra point of swung weapon damage – and sets your hit points (equal to ST) and lifting capacity (a function of the ST squared). So while a T-Rex and a squirrel can both have DX 11, HT 10 (as an example), that T-Rex might have ST 50, and the squirrel ST 1 or ST 2. One can and does make die rolls against ST in some cases, and in the past, I’ve noted that it wasn’t my favorite game mechanic.

Do I still not like ST rolls?

Yeah, I still think they need to die.

But a while ago, I penned a bit on grappling at low ST that had the right kind of thing going for it.

Recently, I’ve been noodling more on this, and there are some interesting concepts that have come to me that are not giving completely stupid results when I start to apply them.

So this will be about building the idea to see what happens.


Power Ratio



The key bit for a lot of this work is the concept of power ratio, or strength-to-weight ratio. The key bit, of course, is that a lot of the performance stuff we’re dealing with here is simply a measure of how much force you can apply (a function of ST), measured against the resistance to that force (an opposing fighter’s ST, or the weight of something you’re trying to lift).

Now, ratios in games can suck. But you can turn a ratio into a sum using logarithms, and a log-based table (the Size and Speed/Range table) is at the core of scaling in GURPS. So if there were a number that related to force or weight, then a quick comparison would then give you a figure for overmatch – basically whether you’ve got the ability to muster enough force to make the job easy or hard.

HT and DX 

The short version here is never roll against ST. ST provides a modifier for what you’re trying to do. But if you’re trying to see if you have the fortitude to pick something up, or are straining at max power against something, you’re rolling against HT. If you’re trying to manipulate things with precision, that’s DX, again penalized by how hard you have to work to simply lift it.

For lifting, higher HT should

Key Numbers


Whatever scaling I decide to use, the results should make sense based on normal GURPS results. Moving around something less than your basic lift should be easy. More than 8-10xBL should be hard. 15xBL (carry on back) More than 50x Basic Lift (the ‘shift slightly’ limit, p. B353) should be impossible or close to it.

The other thing that will have to be guarded against is having HT become the primary driver of lifting power rather than ST. This would be easy to see – if the penalties for climbing up a power ratio are mitigated more strongly by increasing HT than ST, you can have a case where it’s better to be ST 10, HT 20 in terms of lifting power than it is ST 20, HT 10.

Scaling



As noted before, “use what’s there” when you can. This means that if we need a log table and we can get away with it, easy modifications to the Size and Speed/Range Table are where it’s at.

That we need to go from 1xBL as easy to 10xBL as hard suggests that the usual -6 penalty for a x10 increase in difficulty isn’t enough. Since the practical range is really 1xBL through 15xBL (7 steps on the SSR table) and we want 15xBL to be really, really hard even for someone of superlative HT, having x10 be somewhere like -9 through -12 would be in the right range.

-9 per x10 is 1.5x the SSR progression. That’s OK, but if you’re going to do logs and math, at that point you might just want to say 10xLog(Weight) so you can simply push one button on a calculator.

But -12 per x10 is interesting, because what it says is that you will need some sort of boost – lifting training or such – to HT rolls in order to max out lifting ability. That’s not tragic. We’ll have to be somewhat careful, though, as the typical penalty to act under 10xBL is -4 to Dodge. Since Dodge is based on Basic Speed, which it itself (DX+HT)/4, then to get to Dodge -4 based on penalties that are applied to each of DX and HT requires around -16 in total penalties, or -8 to each of DX and HT. -9 would work as well, and -10 would be Dodge -5 instead of -4.

So the -12 scaling rate would work OK if 1xBL were a roll at +4 and 10xBL is -8. Again, that seems to not be crazy-talk. 

And going from 10x BL to 50xBL? That’s another 4 steps on the SSR table, so it’d be an additional -8 penalty . . . -16 if we pegged the scale as it was before (that puts no penalty as 2xBL, more or less, for what it’s worth).

If we want to match the current encumbrance scaling, we’d set the no penalty level to 20 lbs (1xBL) and -8 at 200 lbs (10xBL). 50xBL would be -14 on that scale. 

The two scales are incompatible. Eventually, a choice will need to be made – likely making a straight-up roll vs some HT-based formula the equivalent of “combat” ability – do what you want, in one second, with no preparation, bracing, etc. And the equivalent of an All-Out bonus (maybe, hopefully equal to the usual +4 for AoA) to add the need to brace and prepare in order to lift high weights.

HT roll as a Parry equivalent



Basing the resistance roll for lifting on straight-up HT makes increasing HT too powerful. Making it something like 3+HT/2 helps mitigate it, as well as taking the bite out of lower HT.

So if we set zero penalty at 1xBL for ST 10, that is, 20 lbs, with that same scaling, some interesting things happen. I’ll explore those at a later date. So how are the results from a consistency perspective?

If we look at 3+HT/2 for a point where you’re rolling vs a 10 (50% chance to snag something easily with no bracing or prep), going from HT 10 to HT 20 boosts that (again, for ST 10) from 30 lbs (1.5xBL) to 70 lbs (3.5xBL). That’s for 100 points. For that same 100 points, you get to 120 lbs, which is 4x higher than the 30-ish lbs. you get at ST 10. So at this juncture, it’s still more efficient to boost ST than HT.

Lifting Skill



For a boost to HT based on training, when just looking at making the lift (can you do it on that attempt), I’d probably look to the Training Bonus used in Technical Grappling. So actual lifting skill in excess of DX would grant a bonus to the roll above (in effect, double bonus to HT). 

One could/should also consider NOT making it a straight roll, so that HT 11 and a +3 training bonus for Lifting skill at DX+2 is worthwhile – it pushes you to the equivalent of HT 14, and helps out with that “but odd values of HT suck for breakpoints!” thing.

In fact, I kinda like that.

Parting Shot


The dynamics of HT and ST just got a bunch more complex. The good news of eliminating ST rolls is balanced by a whole lot of potentially suspension of disbelief generating emergent behavior as the interactions of all of this are realized. 

This is a bit of a ground-up redsign of the ST and encumbrance rules. The usual penalties and bonuses for having a certain multiple of BL for break points and its impact on Dodge could easily turn into an all-out penalty to skill as well. That would turn heavy armor from “oh, that’s heavy, it impacts my Dodge” into “that’s crippling and hits my ability to do anything to a ridiculous degree.”

Perhaps easy to fix: that weight only impacts move and dodge, perhaps, and you only suffer DX penalties when trying to manipulate the entire weight. So you might be at -4 to DX and HT trying to throw  50 lbs of armor, but no penalty to DX and -2 to Dodge while wearing it.

The next step in bringing this into an actual system for rules would be to turn this around, and instead of using a spreadsheet to look at well-paced increments on the Size and Speed/Range table, to think about setting things up in terms of penalties based on Basic Lift.

The numbers will look weird. You’ll be looking at a 12-step progression – basically twice the resolution of the usual SSR table, and that means the progression to be memorized looks like this:

0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12
1 1.25 1.5 1.75 2 2.5 3 4 5 6 7 8.5 10

with the bolded numbers being the usual SSR table. 

It’s a fairly punishing progression. A 50-lb load against a 20-lb basic lift is -5, which will wind up being about -2.5 to Dodge. That’s higher than the roughly -1.5 it is now (it’s really -2, since you’re above 2xBL). Favoring the defense by dropping fractions will be the order of the day here – already a departure from GURPS standard procedures. That would move the Dodge breakpoints to 

-1 to Dodge at higher than 1.5xBL (that’s a break for the player)
-2 to Dodge at higher than 2xBL (break even)
-3 to Dodge at 3xBL (same as usual)
-4 to Dodge at 5xBL (harsher than RAW)
-5 to Dodge at 7xBL (this level of penalty doesn’t even exist)
-6 to Dodge at 10xBL (quite a bit harsher than the usual -4)

At least that value is independent of HT; it’s just power ratio based which is good. The ability to lift weights at a given power ratio, at least in one turn? That becomes strongly HT-based. 

What that might turn into is to leave go any temptation of inflicting injury on a failed HT roll. Instead, you’ll be saying that a successful HT roll completes the lift. A failed one (maybe fail by less than a certain margin) means you move the weight but not to the full range of motion (that might be how we get from 10xBL to 50xBL for “shift slightly”). Only on a crit fail, or some sort of double botch (start the weight moving, then fail it, then fail a DX or HT roll to keep it stable or immobile or something) might you pull something, or try and drop the weight but drop it on yourself instead.

This is how I tinker with rules when I’m in full-on tweak mode. It ain’t pretty. It involves lots of trial-by-spreadsheet and Goal Seek and trial-and-error.

It usually winds up somewhere I like (see The Deadly Spring, The Last Gasp, On Target, etc). But sometimes, it doesn’t

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