Here's a basic formula that i'm working on. I prefer hitting locations (like in Martial Law) but i don't like the way PC's in plate armour are basically immune in those tables.
I'm going to use the basic crits from the Harp Core rulebook, then this is modified by the area hit.
The location you hit is determined by a single attack roll (same as Martial Law)
The tens dice is left or right (odds=left, even=right)
The unit dice will tell you the location;
1=feet, 2=legs, 3=hands, 4=arms, 5=groin, 6=abdomen, 7=chest/back, 8=shoulders/upperarms, 9=neck, 10=head
Called Shot. You declare before you roll what modifier you wish to have. Each +1/-1 is a -20 to OB ..... (not sure about this number, still working on it. It's -10 in the book) So, an example ... if i see a warrior with plate breastplate, no leg greaves, leather boots, a plate helmet and leather gaunlets i might think "right i want to hit him on the legs to slow him down" So i declare a called shot of +/- 3, that's -60 OB but i can go up or down the chart by 3 steps. My attack roll is 84, normally hitting his right arm. I decide to modify the roll with my called shot, lower it by 2 and hit his exposed right leg.
I'll use the slash crit results as an example;
51-60 = 16H
61-70 = 18H, 1S, -10
71-80 = 20H, 1S, 1B,-15
Those are the basic crit results from Harp Core. In my system those results are the same as hitting the Chest/Back. If you hit another area there's a simple modification for each area (eg. Head/Neck= +10H, 1S, 1B, -10) So that means if i get a result of 77 and hit the foes head it'll be 30H, 2S, 2B, -25 ........ All the minuses represent either tendons cut (slash crits) bones broken (crush crits)
Please note..... you won't have to work out the modified location hit. A crit table with 5 columns (legs/feet, head/neck, etc) will be written.
Here's what i'm thinking of using as modifiers for each area;
Head/Neck - +10H, 1S, 1B, -10
Hands/Arms - 5H, 1B
Legs/Feet - 3H, -10
Chest/Back - as normal core crits
Abdomen/Groin - 8H, 1S
The area hit is modified by the protection/armour (similar to Martial Law, but changed slightly. I thought plate was too good)
No Armour = +15H, 1S, 2B, extra -10
Soft Leather = +10H, 1S, 1B, extra -5
Rigid Leather = +5H, 1B
Chain = as normal
Reinforced Chain = -5H, -1B, -5 less
Plate = -10H, -1S, -2B, -10 less
I'm currently working on all the descriptions. (smashed knees, cut tendons, teeth knocked out etc)