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= Resident Evil 4
= Rank Analysis (Version 0.3.1)
= GameCube (GC) - Playstation 2 (PS2) - PC - Wii
= Thanks to Pacaya_fr for the magic value of 3500
= By Skullbot

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Note : All of these calculations have been made on a Gamecube Debug Version, then verified with 2004 PC & Steam releases of the game.
             
The rank, or difficulty adjustment, is a numeric value between 1 and 10.
It modifies damages you receive, you deal (or maybe enemy health instead), critical headshots chances, and even hitboxes sizes.
There's also some enemies which spawns only when the rank is high enough.
So it's a really interesting thing to control when you speedrun the game.
But in order to do this, you should understand how it works first.
 
Rank is divided in two parts : a value between 1 and 10, and another one between 1000 and 10999.
The first is the actual rank, while the second is the rank "progress bar".
The rank (first value) is always equal to the first digit of the "progress bar" (two digits if 10000+).
Example : When the bar is at 5943, the rank is 5.

The calculation is something like this :    
MOD = BASE x RANK_RELATED_MODIFIER?
           
Where MOD is the actual gain or loss on the progress bar and BASE a defined amount of points for a given action.
The RANK_RELATED_MODIFIER value is yet unknown but is used to make it as  :
   - The HIGHER the rank is, the faster it will DECREASE.
   - The HIGHER the rank is, the slower it will INCREASE.
   - The LOWER the rank is, the faster it will INCREASE.
   - The LOWER the rank is, the slower it will DECREASE.
 
======================== Difficulty Modes ======================
EASY    : Rank = RankValue / 2000 (Base RankValue = 4500 )
Note    : Rank can't go higher than 6 in this mode. All gains and loss are divided by two.
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NORMAL  : Rank = RankValue / 1000 (Base RankValue = 5500 )  
Note    : PAL version seems to begin at 3500.
Note    : Those values applies to Separate Ways, Assignment Ada and probably Mercenaries.
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PRO     : Rank = 10    (Base RankValue = 10999 )  
Note    : Rank is always maxed out.
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The following values have been calculated with a rank of 5. (Default)
Keep in mind that all these values are empiric and still needs some research.
 

======================== Doesn't affect the rank ======================== Kill a chicken, a spider, the merchant
Kill an enemy by blowing up his dynamite
Use healing item
Pick up healing items
Pick up ammo
Pick up treasures
Kick an empty ladder
Destroy a shield
Throw/miss a flash grenade
Throw/miss a fire grenade Take ground fire damage
Cut into the air
Miss a rocket (killing no one)
Miss shots with Chicago Typewriter
Let Ashley get caught
======================== Lower the rank ======================== Missed shot with TMP / Thompson : -1 Missed shot with handgun : -5 Missed shot with shotgun : -13 Missed shot with striker : -15 Missed shot with super magnum : -25 Missed shot with grenade (no hits/kills) : -25 Missed shot with mine-thrower (after explo) : -25 Missed shot with sniper : -50
Let Ashley take damage : -400 (Further research needed on damage power) Take damage : -400/-500 (See dedicated section : Damages) Getting caught and miss the QTE : -800 (Probably counted as two small damages) Game over : -800 (See dedicated section : Game Over) ======================== Raise the rank ======================== Damage an enemy¤ (weapons or cut) : +2 Dodge an attack : +50 Offensive QTE (Kick, Suplex) : +50 Make an enemy fall off a ladder : +55 Explode static dynamites (on walls & trees) : +60 Kill an enemy¤ : +75 Enemy suicide : +75 Kick a ladder with an enemy on it : +100 Critical headshot : +127 (Base 50 + 75 for the kill + 2 for the inflicted damage) Krauser dodge QTE validation : +150 (Base 100 + 50 attack dodge)

  ¤ Enemies here are every ganados & plagas, but also cows and crows. Bats also count but only for damages done (+2).
             

======================== Dedicated section : Damages ======================== Enemies's attacks seems to be separated in two categories, strong and weak. Mostly, weak attacks are the villagers ones. Strong ones are mostly in the castle and the island.

Here a list of tested attacks :
----- WEAK -----
Knife                           : -400
Sickle                          : -400
Crossbow bolt            : -400
Bear trap                    : -400
Get caught		      : -400
Krauser's low kick        : -400
----- STRONG -----
Dynamite                   : -500
Electric dildo               : -500
Flail                             : -500
Garrador's claws         : -500
Gatling shot                : -500
Krauser's arm blade    : -500
 

======================== Dedicated section : Game Over ======================== Game over rank point loss isn't as easy as the others. Indeed, the loss is not applied to the rank when you die, but instead at the rank you had on the last checkpoint. Checkpoints are mostly loadings rooms, and some cutscenes. Checkpoints are refreshed after a death, in order to apply the next death to the rank you have after your first death. Finally, all game over are the same, Leon or Ashley's death/capture all lower the rank by the same amount. At rank 5, a game over is a 800 points loss.

======================== Dedicated section : Rank reset ======================== In the game, there's some places where the rank got reset to it's default value (based on difficulty). At most boss fights the game will normalize the rank back up to 5500. You can prevent this by choosing retry or dying / killing ashley in the area where you encounter the boss.¤¤

Known bosses fights which resets the rank :
 - Del Lago 
 - El Gigante #1 
 - El Gigante #2 
 - Mendez 
 - Verdugo 
 - Salazar 
 - U3 
 - Krauser

¤¤After some testing, it was discovered that there was no rank/difficulty reset after Del Lago or the first Gigante. This has led me to believe that at no point during the game does the rank/difficulty reset, unless this is proven otherwise. - Outrage