crippling has nothing to do with damage, its an aimed attack crit effect. Also the crit fail table is as follows.
Partially reverse-engineered Fallout 2 combat algorithm
April 21, 2009
This is a brief report on the progress made by Ghosthack and Atom during few days of reverse-engineering
fallout2.exe. The formulas are exact (not extrapolated), taken directly from the executable. There is still
much code in there yet to be understood, but we’ve already managed to extract the basic mechanics of
critical failures in this manner.
Here’s how single attack is resolved:
Assume that the ATTACKER is trying to attack a TARGET with a valid mode of attack. Let TOHIT
be the displayed chance for a successful attack.
The following steps are carried out:
0. The pre-shooting phase:
This part isn’t explored yet in any kind of detail. This is the moment when the TARGET can be changed
to another potential target on the same line of fire. As it isn’t known how the ingame mechanics handle the
case of such a switch occuring we’ll assume that it didn’t and the ATTACKER had ultimately retained his
original TARGET.
1. Basic attack resolution:
Let RND = Random (1, 100). If TOHIT − RND < 0 then the attack was a miss, otherwise it was a hit.
The same value of RND is then used to calculate if the attack was a critical one.
2a. If the attack was a hit:
There’s a possibility of upgrading the ”regular” hit to a critical hit.
Let CRITCHANCE be a total critical chance bonus (for the players it’s a sum of Luck, the Finesse trait
bonus which is either 0% or 10%, 5% for each level of More Criticals perk and aimed shooting to-hit penalty,
why for the other critters it also depends on the stats from their .pro files).
The chance for a hit to be upgraded to a critical hit is then
(CRITCHANCE + Trunc ((TOHIT − RND)/10))%.
If this upgrade fails, then there’s a second chance for the hit to upgrade depending on whether the player
has picked the Slayer or Sniper perk and the type of the attack.
2b. If the attack was a miss:
There’s a possibility of upgrading it to a critical miss, just as with the hits, and it equals
Trunc ((RND − TOHIT )/10)%.
The reason for RND and TOHIT being in a reverse order is of course that of TOHIT − RND being
negative in this case. If the hit fails to upgrade but the ATTACKER is under the Jinxed effect (obtained
from either the trait or the perk given by the pariah dog - their effects don’t stack) there’s a 50% chance for
the miss being upgraded to a one critical anyway.
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3. Assuming that the attack was a critical miss, as the critical hit effects are fairly well
documented (and so are the generic hits and misses):
Let ROLL = ( Random (1, 100) − 5 · (LK − 5)). ROLL is compared with several thresholds to determine
the position of the critical failure on the table (the critical hits are resolved in a similar manner but with a
+0/+20 modifier depending on the Better Criticals perk instead of −5 · (LK −5) depending on LK). The
actual tables vary from weapon to weapon, but in general:
if
ROLL 20 then EFFECT = 0,
20 < ROLL 50 then EFFECT = 1,
50 < ROLL 75 then EFFECT = 2,
75 < ROLL 95 then EFFECT = 3,
95 < ROLL then EFFECT = 4.
As one can see there are five possible critical miss effects. As a rule, the larger the value of EFFECT,
the more severe it will be.
Remark: With LK = 1 it’s impossible to get EFFECT = 0. With LK > 5 it’s impossible to get
EFFECT = 4. With LK = 10 it’s impossible to get either EFFECT = 3 or EFFECT = 4.
There are seven tables used in determining what the actuall effect of the criticall miss will be. Those
are:
type0 for all unarmed weapons,
type1 for all melee weapons,
type2 for all small guns and all big guns except the rocket launcher and both flamers,
type3 for all energy weapons,
type4 for all grenades,
type5 for the rocket launcher,
type6 for the flamer and the improved flamer.
The actual tables are:
type0 (all unarmed)
EFFECT effects
0 miss
1 lost next turn
2 lost next turn
3 took %d damage, knocked down, hurt self
4 crippled random limb (NOT the eyes)
type1 (all melee)
EFFECT effects
0 miss
1 lost next turn
2 weapon dropped
3 hit randomly
4 took %d damage, hit self
type2 (all small guns and all big guns except the rocket launcher and the flamers)
EFFECT effects
0 miss
1 lost rest of ammo
2 weapon dropped
3 hit randomly
4 weapon destroyed
2
type3 (all energy weapons)
EFFECT effects
0 lost next turn
1 lost next turn, lost rest of ammo
2 lost next turn, weapon dropped
3 hit randomly
4 took %d damage, weapon exploded, lost next turn
type4 (all grenades)
EFFECT effects
0 fired dud shot
1 weapon dropped
2 took %d damage, weapon dropped, hurt self
3 hit randomly
4 took %d damage, weapon exploded
type5 (rocket launcher)
EFFECT effects
0 lost next turn
1 fired dud shot
2 weapon destroyed
3 hit randomly
4 took %d damage, knocked down, weapon exploded, lost next turn
type6 (flamers)
EFFECT effects
0 miss
1 lost next turn
2 hit randomly
3 weapon destroyed
4 took %d damage, on fire, weapon exploded, lost next turn
Remarks:
• In general, the effect types are written in the order in which they appear in the combat log.
• The ”miss” effect behaves like a normal miss, no ”critically missed” message is displayed.
• As for the ”took %d damage”, this is yet to be tested, but the following is conjectured:
for dropped grenades the damage received is the same as in type0/effect 3 while in the other cases the
damage depends on the type of weapon used, most probably the damage being equal to one received
by simply being shot by that weapon or its explosion in case of the grenades. It is not known if these
damages can pierce armor.
• ”on fire” in the last effect in type6 triggers the flamedance animation.
• First two effects in type5 seem to be bugged, as ”fired a dud shot” is less severe than ”lost next turn”.
• The exact behavior of ”hit randomly” is not fully known. With this effect it is possible to hit another
target on the map instead of the original one (this is the second instance where the final shot receiver
can be changed - the first was in the pre-shooting phase). Also, sometimes just a ”hit randomly”
message can be displayed, most commonly when there were no valid targets. It’s not known if these
redirected shots can be upgraded to critical hits.
• The ”miss” effect in type6 can still cause damage to the target - as is the case of every missed shot
with a flamer.
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