Revisiting using Knowing Your Own Strength with Conditional Injury in GURPS

All the way back in September 2019, I made a post on how to use “Knowing Your Own Strength” from Pyramid #3/83: Alternate GURPS IV with “Conditional Injury” from Pyramid #3/120: Alternate GURPS V in GURPS. For five months, I worked on it, but I just wasn’t figuring it out; so, back in March, I messaged dataweaver on the GURPS forums, and I asked for their help in moving forward with combining the systems.

  • ST = 20 × log(BS_ST) – 10.
    • ST = VT.
      • VT (Vitality) replaces HP at 2 points/level.
    • BL = 2 × 10(ST / 10).
    • For static damage (like firearms), ST = 20 × log(BS_damage / 0.5547) / log(10).
    • For DR, use the static damage formula and add 14. This is Armor Rating (AR).
    • For muscle-powered weapons, double the modifier, add 10, then log-subtract 9. This is the Weapon Rating (WR). Log-add WR to ST.
    • For damage bonuses (for punches, All-Out Attack, etc.), use them as a bonus to ST—use double the amount as a ST bonus if the damage bonus is per die.
  • Severity = 5d6D2 + ST – VT.
    • D2 means drop two, so drop the lowest two dice.
    • Log-subtract AR before subtracting VT.
    • 5d6D2 averages to 14. I usually just substitute 4d6.
  • Conditional Effects Table:
    • Negative Severity: Nothing.
    • 0 to 4: Scratch, Shock -0, HT+6.
    • 5 to 9: Scratch, Shock -1, HT+5.
    • 10 to 14: Minor Wound, Shock -2, HT+4.
    • 15 to 19: Minor Wound, Shock -3, HT+3.
    • 20 to 24: Major Wound, Shock -4, HT+2.
    • 25 to 29: Reeling, Shock -4, HT+1.
    • 30 to 34: Crippled, Shock -4, HT+0.
    • 35 to 39: Mortal Wound, Shock -4, HT-1.
    • 40 to 44: Mortal Wound, Shock -4, HT-2.
    • 45 to 49: Instantly Fatal Wound, HT-3.
    • 50 or more: Total Destruction.

For the Multiple Injuries rules, I use the above HT rolls for wound accumulation. Log-addition and log-subtraction use the table below. For log-adding two values, look up the difference between the two values in the Log-Addition column, then add the Modifier to the higher value. For log-subtracting two values, look up the difference between the two values in the Log-Subtraction column, then subtract the Modifier from the higher value.

Log-Addition Log-Subtraction Modifier
0 +6
1–2 +5
3–4 +4
5–7 +3
8–10 +2
11–18 +1
19–25+* 26+ +0
26–35 16–25 -1
36–38 13–15 -2
39–41 10–12 -3
42–43 8–9 -4
44 7 -5
45 6 -6
46 5 -7
47 4 -9
48 3 -11
49 2 -14
50 1 -19
51+ 0 -∞

*For WR, use the rest of the chart.

I still need to figure out how to adjust throwing, collisions/slams, and grappling. That shouldn’t be too hard, but I just haven’t given it thought. Additionally, Innate Attack and Damage Resistance need to be reformulated as well, which I think will be a bit trickier.

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