Heavily modified (logarithmic) damage system for GURPS: feedback wanted!

[Sam Baughn]

Inspired by Douglas Cole's Conditional Injury, but applying the logarithmic concept to every part of the GURPS damage process except recording injury, my system makes resolving damage quicker and easier.

Provisional name is 'Sort-Of Logarithmic Improved Damage System' or SOLIDS.

Features:

• Removes almost all division and multiplication calculations, replacing them with addition and subtraction.
• Reduces amount of dice rolled.
• Much faster resolution of multiple hits.
• Handles extreme values easily.
• Introduces mass-based collision and knockback rules for more accurate 'game physics'.
• Smaller numbers, less counting needed.
• Handles small / weak characters better than default system.
• Crippling and major wound thresholds do not need to be calculated for each character.
• Effects which should scale with HP but don't, like bleeding, handled better.
• Fully compatible with most popular optional rules, including Conditional Injury, Knowing Your Own Strength, and Survivable Guns. Actually makes them easier to implement in many cases.
• Potential for future optional rules to be added, taking advantage of features such as easily adding 'wounding modifier' between pi and pi-, 'armor divisor (1.5)', or more precise crippling thresholds (e.g. legs could easily be made slightly harder to cripple than arms, different injury needed to cripple with different damage types).

Drawbacks:

• Slightly less detail than existing rules, some ST scores no longer offer much difference (mostly fixed by combining with Knowing Your Own Strength).
• Some weapons no longer distinct from each other (notably, .45 ACP, .40S&W, and 10mm Auto usually deal the same damage).
• Adds several new numbers; mostly replacing existing ones, but overall count of things on character sheet goes up by at least one (Mass Class).
• Requires extensive conversion of existing items, replacing all HP, DR, and Damage (including armor divisor) values, and adding Mass Class (but conversion tables and formulas are provided).
• Requires some table look-ups (but progression is usually the same as the S&S/R Table, so it may be possible to make a cheat-sheet which covers all needed ones, and if you have the S&S/R Table memorized, you usually just need to 'shift' it a couple of steps).

At the moment, this is very much a 'first draft' which should be useable as-is, but could do with a lot of editing, proof-reading, and playtesting to bring it up to standard. I'd really appreciate any feedback people here can provide.
Anyway, here's the link (125 kB PDF):
https://drive.google.com/file/d/1rxt...ew?usp=sharing

[Varyon]

I like it, although something seems off. I decided to see what would happen if an unarmored, HP 10 character took a hit from a 2d+2 pi weapon (like a 9mm pistol). That would average around 7 HP Injury in the default rules, but I'm getting an average of 4.67 DP, which is off by around 1 SSR. You currently have a result of 1-2 on the damage roll be equal to 1, then 3 is 2, and it's +1 SSR beyond that; I think having 1 -> 1, 2->2, 3->3, 4->5, and so forth, following SSR, may work better (above, this gives us exactly 7 DP as an average).
(EDIT: Also, I'd suggest a damage result of exactly 0 DP to result in -1 Shock but no Injury, like a Severity -6 Scratch in Conditional Injury)
(EDIT2: Math error - 2d+2 pi should average 9 HP Injury, so the initial results were off by around 2 SSR. When I get some time later I'll run some tests vs an HP 10, unarmored character, to see how far off other damage results are)

Also, I notice it looks like you have opted to use SSR rounded down (so 4 becomes 3), rather than GURPS' normal trend of rounding SSR up (so 4 becomes 5). I think for consistency's sake, maintaining the "round up" trend for SSR would work better.

I'll also want to take a look at how this impacts muscle-powered weapons. The loss of resolution has the potential to have significant impacts there, where differences tend to be around +1 to damage. I do like that this allows Swing to simply be +1 DV compared to Thrust, however, and that things like Weapon Master (which seems like it's basically just +1 DV) no longer have large breakpoints when Striking ST is involved.

[Sam Baughn]

Thanks, Varyon. I tweaked numbers repeatedly as I was writing it, so it's very possible that my assumptions about what damage value equated to what drifted by one or two points as I did. If the issue can be fixed simply by reducing all Toughness Ratings by one or two, that is easily done, at least.

Originally Posted by Varyon

You currently have a result of 1-2 on the damage roll be equal to 1, then 3 is 2, and it's +1 SSR beyond that; I think having 1 -> 1, 2->2, 3->3, 4->5, and so forth, following SSR, may work better...

Remember that the S&S/R Table actually goes 1, 1.5, 2, 3, 5... All I did was round down 1.5 HP loss to 1 (it could easily be rounded up to 2, giving 0, 1, 2, 2, 3, 5... but I prefer 0, 1, 1, 2, 3, 5... for purely aesthetic reasons, because it looks nicer on a graph and mimics the Fibonacci sequence). The rest of the sequence is intact, just shifted a few steps (I could have made it so it matches the S&S/R Table exactly, but I thought 0 equating to 'no damage at all' was more intuitive than setting that result to -3; not sure if being able to just use the S&S/R Table without modification would be useful enough to justify losing that).

Originally Posted by Varyon

Also, I notice it looks like you have opted to use SSR rounded down (so 4 becomes 3), rather than GURPS' normal trend of rounding SSR up (so 4 becomes 5). I think for consistency's sake, maintaining the "round up" trend for SSR would work better.

I used both approaches in different places, because I was concerned that I was creating some dubious break-points. For example, if damage went 3d+1 to 5d: DV 10, 5d+1 to 7d: DV 11, 7d+1 to 10d: DV 12, then rifles doing 5d+1 would be way better than ones doing 5d, and ones doing 7d+1 would be significantly better than those doing 7d, which is a big issue because a couple of really popular rifles sit at exactly those points. Making 7.62x39 about half again as good as 5.56 would lead players to strongly prefer Kalashnikovs to their NATO equivalents, while having .30-06 be 50% deadlier than .308 would be even more jarring.
However, it might be better to just stick to a consistent standard and tweak the results for balance on a case-by-case basis.

[Varyon]

Originally Posted by Sam Baughn

Thanks, Varyon. I tweaked numbers repeatedly as I was writing it, so it's very possible that my assumptions about what damage value equated to what drifted by one or two points as I did. If the issue can be fixed simply by reducing all Toughness Ratings by one or two, that is easily done, at least.

Yeah, it looks like shifting it one slot works - which conveniently works out to HP 10 having TR 10.

Originally Posted by Sam Baughn

Remember that the S&S/R Table actually goes 1, 1.5, 2, 3, 5... All I did was round down 1.5 HP loss to 1 (it could easily be rounded up to 2, giving 0, 1, 2, 2, 3, 5... but I prefer 0, 1, 1, 2, 3, 5... for purely aesthetic reasons, because it looks nicer on a graph and mimics the Fibonacci sequence).

Rounding down to 1 does indeed look better, and meshes with some precedents (Spaceships sets DR 15 as dDR 1, for example). Having run the numbers, rounding up is actually closer to the default injury, but it's not going to break anything for you to round down. Something interesting I found when throwing things into a spreadsheet - at least against a target with HP 10, this system consistently results in average injury that's a bit less than the default (although shifting by 1 step makes it instead markedly more than the default).
(EDIT: That last bit was poorly written. Shifting by 1 step - making characters with HP 10 have TR 10 - still has average wounding less than RAW. Shifting a further 1 step makes average wounding be more than RAW. For the curious, the currently-presented system puts average wounding around 50% of RAW, shifting 1 step - my suggestion of reducing TR by 1 - puts it at around 87% of RAW, and shifting 2 steps puts it at around 135%.)

And, yeah, one issue you can run into when making systems like this is at the breakpoints.

[Anthony]

It has the same problem most of my attempts at revising damage have run into: it's actually a lot of rules.

[RyanW]

Looks a lot like my perpetually WIP system. I'll have to tear into it later.

[ericthered]

Why do you add four to the modified damage value if the armor value is 0? What if the damage value is 2?

[Varyon]

Musing on this some more, how much thought have you put into how muscle-powered weapons behave? In theory you could keep a note of how much ST-based damage your character "should" do, and toss in the Adds from the weapon to recalculate DV. But that's going to slow things down if a character has to pick up a new weapon during combat, and you also get similar breakpoints as what "round up" would give you between the M16A2 and the AK47, where using a slightly higher-damage weapon functionally boosts damage by x1.5.

I wonder if you could use something more akin to the way layering armor works. That is, instead of a weapon doing thr+2 imp, it's instead something like DV 6. If you have DV 3-5* (from ST), this makes your damage with the weapon be DV 7. If you have DV 6, it's DV 8. If you have DV 7-9, the weapon gives you +1 to DV. If you have DV 10+, you may need to check your strength to use it (much like how current weapons are limited to damage based on 3*MinST), restricting it to DV 10. For cut/imp Weapons of Quality, perhaps Fine gives +1 AM (so better at getting through armor, but no better at wounding unarmored foes), while Very Fine gives the better of +1 AM and +1 DV (so it performs better against unarmored foes... and against those with hardened armor). Might be worth playing around with. Of course, this makes Striking ST intermediate between two DV's useless - but honestly, I think with a system like this, you'd be best served breaking ST up into TR (which would start at 10 and arguably be [+25]/level, although having it ramp up to this - [10], [10], [20], [25], to mimic HP's pricing at lower levels - might be appropriate), BL (following Lifting ST's pricing - or KYOS), and DV (which would start at 5; I'm not sure exactly what would be fair pricing, here).

*The need to match MinST - or MinDV if taking my later advice - may mean you can only have DV 1 or 2 points below that of a typical weapon.

EDIT: Looking at the document again, I see you did have some information on muscle-powered weapons, but it was such that you simply get a flat boost to DV based on the weapon's Adds, which seems excessive. I think revamping the table, with weapons having their own DV that "stacks" with your personal DV as above, would work better. Weapons that are rescaled for a character's ST/DV would actually be fairly simple - every +1 to weapon DV increases MinDV (probably weapon DV -2 for most weapons) and MaxDV (weapon DV +3 for most weapons) by +1, and increases weight by +1 SSR. Generally revamping tables is probably appropriate for this system, along with lumping a lot of similar weapons together, with the exact weapon being more flavor than stats - you don't have M16A2 vs AK47, you just have an Assault Rifle; you don't have Longsword vs Katana, you just have a Hand-and-a-Half Sword. And so forth.

[Sam Baughn]

I put a fair bit of thought into melee weapons and tried a lot of different ways to calculate damage, then settled on the simplest option. It looks like I should have put more thought into it though, because the 'layering' method you propose is brilliant and should work a lot better.

I'm considering dropping Armour Modifiers and just increasing Damage Value and dropping Injury Modifier by the same amount instead. I maybe need to consider it when I'm less tired, but as far as I can see, there's basically no difference between (AM -2) and (DV+2, IM-2). Not sure it actually makes things simpler though; removing one stat seems like a step in the right direction, but it means adding another step in calculating Injury Modifier.

[Varyon]

Originally Posted by Sam Baughn

I put a fair bit of thought into melee weapons and tried a lot of different ways to calculate damage, then settled on the simplest option. It looks like I should have put more thought into it though, because the 'layering' method you propose is brilliant and should work a lot better.

Don't give me too much credit, here - it's just your armor layering rules, applied to damage. I suspect the way to calculate what a given weapon's DV is would probably be to calculate the RAW damage for it using ST equal to MinST, and applying the weapon's Adds to that, but it's something you'll want to play with a bit.

Originally Posted by Sam Baughn

I'm considering dropping Armour Modifiers and just increasing Damage Value and dropping Injury Modifier by the same amount instead. I maybe need to consider it when I'm less tired, but as far as I can see, there's basically no difference between (AM -2) and (DV+2, IM-2). Not sure it actually makes things simpler though; removing one stat seems like a step in the right direction, but it means adding another step in calculating Injury Modifier.

Armor Divisors struck me as a great idea when I first saw them in GURPS, and I think getting rid of them would cause more issues than it would solve. Really, I think "Apply this modifier to AV before comparing it to DV" is sufficiently simple. It's one number (the modifier) and one operation (apply modifier), rather than one number (again, the modifier) and two operations (apply the modifier to DV, then apply the opposite of the modifier to IM)... or two numbers (one for DV, one for IM, with each being the opposite of the other) and two operations (applying each to DV and IM).
EDIT: Consider if, instead of an Armor Divisor, GURPS had opted to multiply damage, then divide wounding by the same factor (IIRC, this is how they handled armor piercing and hollowpoint bullets in Fallout: New Vegas, to get around inherent shortcomings of the Fallout 3 engine it was built on top of; of course, it works there because it's a computer handling everything, but some sort of armor divisor/multiplier would have called for less computation and been overall cleaner). The latter is clearly more complicated - and more prone to accidental errors of calculation - than the former.